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 of the following statement is true?

To determine the correct statement, we can systematically construct a table representing the sequence of months, the students, and the birds they are studying. Let's list the months in chronological order along with the number of days in each month:

1. January (31 days)
2. March (31 days)
3. May (31 days)
4. June (30 days)
5. July (31 days)
6. October (31 days)
7. November (30 days)
8. December (31 days)

Step 1: Determine G's position
- We are told that G is studying in a month having an odd number of days (31 days), and either two persons study before G or two persons study after G.
- If two persons study before G, G must be in the 3rd position (May, 31 days).
- If two persons study after G, G must be in the 6th position (October, 31 days).
Let us analyze the case where G studies in the 3rd position (May).

Step 2: Locate the person studying Loon
- There are two persons studying between G and the one studying Loon.
- Since G is in the 3rd position, the person studying Loon must be in either the 6th position (October) or the 1st position (January).

Step 3: Analyze H and A
- We know that H studies four months before A (in calendar months, not positions). Let's check the month pairs with a gap of exactly 4 months:
- January (1) and May (5)
- June (6) and October (10)
- July (7) and November (11)
- We are also told that H studies three persons after the person studying Ostrich. This means:
$Position(H)\; =\; Position(Ostrich)\; +\; 3$.
- If H is in June (4th position) and A is in October (6th position):
- Ostrich must be in January (1st position), since $4\; -\; 3\; =\; 1$. This is a valid configuration.
- Thus, the person studying Loon (which was either 1st or 6th) must be at the 6th position (October) because the 1st position (January) is already taken by the person studying Ostrich.
- Therefore, A (October) is studying Loon.

Step 4: Locate Woodpecker
- Three persons study between A (6th position) and the one studying Woodpecker.
- This places the person studying Woodpecker in the 2nd position (March), since $6\; -\; 3\; -\; 1\; =\; 2$.

Step 5: Place B and F
- B is studying Sparrow, two persons before F. This means:
$Position(F)\; =\; Position(B)\; +\; 2$.
- The available positions for B and F are 5 (July) and 7 (November).
- Thus, B (Sparrow) is in the 5th position (July) and F is in the 7th position (November).

Step 6: Place the remaining persons
- F is studying before E. Since F is at the 7th position, E must be at the 8th position (December).
- The remaining positions for C and D are 1st (January) and 2nd (March). Since D is not the first one to study, D is at the 2nd position (March) and C is at the 1st position (January).

Step 7: Determine the remaining birds
- The one studying Penguin studies immediately after the one studying Kingfisher. This consecutive pair must be at the 7th (November, F) and 8th (December, E) positions respectively.
- Thus, F studies Kingfisher and E studies Penguin.
- Two persons study between the ones studying Kingfisher (7th position) and Peacock. This puts the person studying Peacock at the 4th position (June, H).
- The remaining bird, Toucans, is studied by G (3rd position, May).

Final Arrangement:
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)

Evaluating the statements based on this final arrangement, we see that A is studying in the month of October is the correct statement.