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: the total age of a and b is 16 years more than the total age of b and c. c is how many year younger than
Options: a. 14 years, b. 12 years, c. 56 years, d. 16 years, e. 55 years
[A]: d

[Q]: Problem: a merchant marks his goods up by 30 % and then offers a discount of 10 % on the marked price. what % profit does the merchant make after the discount ?
Options: a. 17 %, b. 25 %, c. 69 %, d. 31 %, e. 19 %
[A]: a

[Q]: Problem: what is the maximum number of points that 10 circles of different radii intersect ?
Options: a. 24, b. 26, c. 33, d. 90, e. 100
[A]:
d