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 car is 15 minutes late by running at a speed of 4 / 5 th of its actual speed. the actual time taken by the car to cover that distance is :
Options: a. 30 minutes, b. 1 hour, c. 2 hours, d. 3 hours, e. none of these
b

Problem: car x began traveling at an average speed of 35 miles per hour. after 72 minutes, car y began traveling at an average speed of 70 miles per hour. when both cars had traveled the same distance, both cars stopped. how many miles did car x travel from the time car y began traveling until both cars stopped ?
Options: a. 15, b. 20, c. 40, d. 42, e. 68
d

Problem: find the probability that a number selected from numbers 1, 2, 3,..., 30 is a prime number, when each of the given numbers is equally likely to be selected ?
Options: a. 10 / 30, b. 1 / 30, c. 8 / 30, d. 3 / 30, e. 7 / 30

c