Definition: 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.
Input: Question: Three unbiased coins are tossed. What is the probability of getting at most two heads?

 Option A: 3/4

 Option B: 1/4

 Option C: 3/8

 Option D: 7/8

 Option E: 5/8

Option D