Eight persons — A, B, C, D, E, F, G and H were studying about different birds in different months of the same year, viz. January, March, May, June, July, October, November and December, but not necessarily in the same order. Each of them is studying about different birds — Kingfisher, Toucans, Penguin, Ostrich, Woodpecker, Loon, Sparrow and Peacock.

G is studying in the month having odd number of days. Either two persons were studying before G or after G. Two persons were studying between G and the one who is studying about loon. H was studying three persons after the person who is studying about ostrich and four months before A. Three persons were studying between A and the one who is studying about Woodpecker. B is studying about Sparrow two persons before F. F is studying before E. The one who is studying about Penguin is studying immediately after the one studying about Kingfisher. Two persons were studying between the ones studying about Kingfisher and Peacock. D is not the first one to study.

Which among the following statement is not true?
I. A is studying about Loon
II. F is studying in the month having even number of days.
III. C is studying in the month after D.

To determine which statement is not true, we can systematically analyze the given clues and reconstruct the schedule step-by-step.

Step 1: Understand the months and their number of days
The eight months in chronological order and their days are:
1. January (31 days - Odd)
2. March (31 days - Odd)
3. May (31 days - Odd)
4. June (30 days - Even)
5. July (31 days - Odd)
6. October (31 days - Odd)
7. November (30 days - Even)
8. December (31 days - Odd)

Step 2: Determine the position of G and the Loon student
G studies in a month with an odd number of days, and either two persons study before or after G. This means G must be at either the 3^rd position (May) or the 6^th position (October).
There are two persons studying between G and the person studying about Loon. Since there are 2 persons between them, if G is 3^rd, Loon must be 6^th. If G is 6^th, Loon must be 3^rd.

Step 3: Place H, A, and Ostrich
We are given that H studies three persons after the person studying about Ostrich (meaning Ostrich is at position x, and H is at position x + 3).
We also know H studies four months before A. Let's find the pairs of months with a gap of exactly 4 months:
• March (3) to July (7) ⇒ H is in March (2^nd), A is in July (5^th). In this case, Ostrich would be at position 2 - 3 = -1, which is impossible.
• June (6) to October (10) ⇒ H is in June (4^th), A is in October (6^th). Here, Ostrich is at position 4 - 3 = 1^st (January). This is a valid configuration.
• July (7) to November (11) ⇒ H is in July (5^th), A is in November (7^th). Here, Ostrich is at position 5 - 3 = 2^nd (March). If so, Woodpecker (who has 3 persons between themselves and A, i.e., position 7 - 3 - 1 = 3^rd) would conflict with G (who would have to be 6^th because 3^rd is Woodpecker, making Loon 3^rd, which is a conflict).
Thus, H must be at the 4^th position (June), A must be at the 6^th position (October), and Ostrich is at the 1^st position (January).

Step 4: Determine G, Woodpecker, and Loon positions
Since A is at the 6^th position, G cannot be 6^th. Thus, G is at the 3^rd position (May).
This placing makes the Loon student occupy the 6^th position (October), which is A. Hence, A studies about Loon (Statement I is true).
Since three persons study between A (6^th) and the Woodpecker student, Woodpecker must be at the 2^nd position (March).

Step 5: Place B, F, and E
B studies about Sparrow two persons before F (so B is at position y, and F is at position y + 2). The only available spots matching this pattern are 5^th (July) and 7^th (November).
Thus, B (Sparrow) is at the 5^th position, and F is at the 7^th position (November).
Since F studies before E, and F is 7^th, E must be 8^th (December).

Step 6: Place C and D
The remaining positions for persons are 1^st (January) and 2^nd (March).
We are told D is not the first one to study. Therefore, D must be 2^nd (March) and C must be 1^st (January).

Step 7: Final Arrangement Table
Applying the remaining clues to fill the birds:
• Kingfisher (7^th) and Penguin (8^th) are adjacent, with Peacock (4^th) being 2 positions away from Kingfisher.
• G (3^rd) studies about Toucans.

The complete schedule is:
1. January: C (Ostrich)
2. March: D (Woodpecker)
3. May: G (Toucans)
4. June: H (Peacock)
5. July: B (Sparrow)
6. October: A (Loon)
7. November: F (Kingfisher)
8. December: E (Penguin)

Step 8: Evaluate the Statements
• I. A is studying about Loon: True (A is at 6^th position, which is Loon).
• II. F is studying in the month having even number of days: True (F studies in November, which has 30 days).
• III. C is studying in the month after D: False (C studies in January, which is before March when D studies).

Therefore, only Statement III is not true.