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: how many prime numbers are between 29 / 3 and 87 / 6 ?
Options: a. 1, b. 2, c. 3, d. 4, e. 5
[A]: b


[Q]: Problem: two taps a and b can fill a cistern in 12 minutes and 18 minutes respectively. they are turned on at the same time. if the tap a is turned off after 4 minutes, how long will tap b take to fill the rest of the cistern ?
Options: a. 8 min., b. 9 min., c. 10 min., d. 7 min., e. none of these
[A]: a


[Q]: Problem: the sum of number of boys and girls in a school is 1150. if the number of boys is x, then the number of girls becomes x % of the total number of students. the number of boys is ?
Options: a. 50, b. 40, c. 60, d. 92, e. 70
[A]:
d