You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Question: The least number of complete years in which a sum of money put out at 20% C.I. will be more than doubled is?

 Option A: 3

 Option B: 4

 Option C: 9

 Option D: 3

 Option E: 5
Option B

Question: If |x^2 − 20| = x, which of the following could be the value of x?

 Option A: -5

 Option B: -4

 Option C: 1

 Option D: 4

 Option E: 10
Option D

Question: What is the unit digit in 8^100?

 Option A: 0

 Option B: 1

 Option C: 6

 Option D: 3

 Option E: 5

Option C