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 percent is 6 gm of 1 kg ?
Options: a. 1.5 %, b. 0.5 %, c. 0.6 %, d. 3.5 %, e. 4 %
[A]: c


[Q]: Problem: if x ^ 2 – 3 x = 18, then one possible value of x – 4 =
Options: a. - 9, b. - 5, c. - 3, d. - 1, e. 2
[A]: e


[Q]: Problem: the cost of paint is 60 per kilograme. a kilogram paint covers 20 square feet. how much will it cost to paint the outside of a cube having each side 10 feet ?
Options: ['a. 3000', 'b. 900', 'c. 1800', 'd. 360', 'e. none of these']
[A]:
c