Study the given information carefully and answer the questions given below.

Nine people A, B, C, D, E, F, G, H, and I were born in different years i.e., 1998, 2000, 2003, 2004, 2005, 2010, 2012, 2015, and 2017 on the same date i.e., 31st December but not necessarily in the same order. Their ages are calculated as of 31st December 2021.

B is two years younger than A. The sum of the ages of C and D is 35, and C is older than D. The ages of F, G, and I are all perfect squares, where I is the youngest of the three and F is the oldest of the three. E is older than H.

Which of the following individuals is the oldest?

The correct option is A.

Step 1: Calculate the age of each person as of December 31, 2021.
To find the age of a person born in a specific year, subtract their birth year from 2021:

$2021-1998=23\text{years old}$

$2021-2000=21\text{years old}$

$2021-2003=18\text{years old}$

$2021-2004=17\text{years old}$

$2021-2005=16\text{years old}$

$2021-2010=11\text{years old}$

$2021-2012=9\text{years old}$

$2021-2015=6\text{years old}$

$2021-2017=4\text{years old}$

So, the set of possible ages is {23, 21, 18, 17, 16, 11, 9, 6, 4}.

Step 2: Determine the ages of F, G, and I.
The ages of F, G, and I are all perfect squares. Looking at the list of ages, the perfect square ages are 16, 9, and 4.
Given that F is the oldest of the three and I is the youngest:
- Age of F = 16 (born in 2005)
- Age of G = 9 (born in 2012)
- Age of I = 4 (born in 2017)

Step 3: Determine the ages of C and D.
The remaining available ages are {23, 21, 18, 17, 11, 6}.
We are given that the sum of the ages of C and D is 35, and C is older than D.
The only pair from the remaining ages that adds up to 35 is 18 and 17 ($18+17=35$).
Since C is older than D:
- Age of C = 18 (born in 2003)
- Age of D = 17 (born in 2004)

Step 4: Determine the ages of A and B.
The remaining available ages are {23, 21, 11, 6}.
We are given that B is two years younger than A.
Looking at the remaining ages, the pair with a difference of 2 years is 23 and 21 ($23-21=2$).
Therefore:
- Age of A = 23 (born in 1998)
- Age of B = 21 (born in 2000)

Step 5: Determine the ages of E and H.
The remaining ages are {11, 6}.
Since E is older than H:
- Age of E = 11 (born in 2010)
- Age of H = 6 (born in 2015)

Conclusion:
Comparing all calculated ages:
- A: 23
- B: 21
- C: 18
- D: 17
- E: 11
- F: 16
- G: 9
- H: 6
- I: 4

The oldest individual is A (age 23, born in 1998).