Explanation:

- Let the present age of the father be 8x and the mother be 7x, since the ratio is 8:7.

- After 8 years, the father’s age will be 8x + 8 and the mother’s age will be 7x + 8.

- The sum of their ages after 8 years is given as 91 years:

\((8x + 8) + (7x + 8) = 91\)

- This simplifies to:

\(15x + 16 = 91\)

- Subtract 16 from 91:

\(15x = 75\)

- Divide by 15:

\(x = 5\)

- Thus, the present age of the father is:

\(8x = 40\) years.

- Option 1: 40 years is the correct answer.