Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[Q]: Problem: a person ' s present age is two - fifth of the age of his mother. after 8 years, he will be one - half of the age of his mother. how old is the mother at present
Options: a. 38, b. 40, c. 42, d. 44, e. 45
[A]: b


[Q]: Problem: the average of first six prime numbers greater than 20 is ?
Options: a. 10, b. 20, c. 30, d. 40, e. 34
[A]: e


[Q]: Problem: when 242 is divided by a certain divisor the remainder obtained is 15. when 698 is divided by the same divisor the remainder obtained is 27. however, when the sum of the two numbers 242 and 698 is divided by the divisor, the remainder obtained is 5. what is the value of the divisor ?
Options: a. 11, b. 17, c. 13, d. 23, e. 37
[A]:
e