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.

Problem: in 10 years, a will be twice as old as b was 10 years ago. if a is now 5 years older than b the present age of b is
Options: a. 37, b. 38, c. 39, d. 35, e. 41
d

Problem: two trains travel in opposite directions at 36 kmph and 45 kmph and a man sitting in slower train passes the faster train in 8 seconds. the length of the faster train is
Options: a. 80 m, b. 100 m, c. 120 m, d. 180 m, e. 160 m
b

Problem: what is the probability of getting a queen or spade from a set of cards ?
Options: a. 3 / 13, b. 4 / 13, c. 5 / 13, d. 6 / 13, e. 7 / 13

b