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.

[EX Q]: Problem: if jack walked 8 miles in 1 hour and 15 minutes, what was his rate of walking in miles per hour ?
Options: a. 4, b. 4.5, c. 6, d. 6.4, e. 15
[EX A]: d

[EX Q]: Problem: 4, 12, 48, 240, 1440, 10080,80640 (... )
Options: a. 7620, b. 10080, c. 6200, d. 10020, e. 725760
[EX A]: e

[EX Q]: Problem: a 160 meter long train crosses a man standing on the platform in 18 sec. what is the speed of the train ?
Options: a. 96 kmph, b. 94 kmph, c. 32 kmph, d. 56 kmph, e. 76 kmph
[EX A]:
c