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: aaron will jog from home at 2 miles per hour and then walk back home by the same route at 4 miles per hour. how many miles from home can aaron jog so that he spends a total of 3 hours jogging and walking ?
Options: a. 5, b. 7, c. 3, d. 9, e. 10
c

Problem: at what rate percent per annum will a sum of money double in 6 years.
Options: a. 12.5 %, b. 13.5 %, c. 11.5 %, d. 14.5 %, e. 16.6 %
e

Problem: for all positive integers m, [ m ] = 3 m when m is odd and [ m ] = ( 1 / 2 ) * m when m is even. what is [ 5 ] * [ 8 ] equivalent to ?
Options: a. [ 40 ], b. [ 60 ], c. [ 80 ], d. [ 120 ], e. [ 150 ]

d