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: a student travels from his house to school at 10 km / hr and reaches school 2 hours late. the next day he travels 18 km / hr and reaches school 1 hour early. what is the distance between his house and the school ?
Options: a. 65.0, b. 67.5, c. 70.0, d. 72.5, e. 75.0
b

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

Problem: when positive integer x is divided by 11, the quotient is y and the remainder is 4. when 2 x is divided by 5, the quotient is 3 y and the remainder is 4. what is the value of 4 y – x ?
Options: a. - 2, b. - 1, c. 0, d. 1, e. 2

c