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.

Input: Consider Input: Problem: in a group of 100 people, 90 have an age of more 30 years, and the others have an age of less than 20 years. if a person is selected at random from this group, what is the probability the person ' s age is less than 20 ?
Options: a. 0.1, b. 0.55, c. 0.65, d. 0.75, e. 0.85

Output: a


Input: Consider Input: Problem: a man ' s speed with the current is 18 km / hr and the speed of the current is 2.5 km / hr. the man ' s speed against the current is ?
Options: a. 10, b. 18, c. 50, d. 30, e. 40

Output: b


Input: Consider Input: Problem: a can finish a work in 18 days and b can do the same work in half the time taken by a. then, working together what part of the same work they can finish in a day ?
Options: a. 1 / 2, b. 1 / 3, c. 1 / 6, d. 2 / 5, e. 2 / 9


Output: c