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.

[Q]: Problem: what sum of money will produce rs. 80 as simple interest in 4 years at 3 1 / 2 percent ?
Options: a. 263, b. 571.4, c. 367, d. 368, e. 339
[A]: b


[Q]: Problem: when positive integer n is divided by 3, the remainder is 1. when n is divided by 7, the remainder is 5. what is the smallest positive integer k such that k + n is a multiple of 21 ?
Options: a. 2, b. 4, c. 6, d. 8, e. 10
[A]: a


[Q]: Problem: if rs. 544 be divided among a, b, c in such a way that a gets 2 / 3 of what b gets and b gets 1 / 4 of what c gets, then their shares are respectively ?
Options: a. s. 300, b. s. 360, c. s. 389, d. s. 384, e. s. 323
[A]:
d