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: 3 ltr of water is added with 9 ltr of a solution containing 57 % of alcohol in the water. the % of alcohol in the new mixture is ?
Options: a. 41.5 %, b. 42.75 %, c. 43 %, d. 45 %, e. 45.75 %
[EX A]: b

[EX Q]: Problem: 5358 x 71 = ?
Options: a. 273762, b. 283758, c. 383298, d. 273258, e. 380418
[EX A]: e

[EX Q]: Problem: the volume of a certain substance is always directly proportional to its weight. if 48 cubic inches of the substance weigh 112 ounces, what is the volume, in cubic inches, of 63 ounces of this substance ?
Options: a. 27, b. 36, c. 42, d. 64, e. 147
[EX A]:
a