Two unbiased coins are tossed. What is the probability of getting at most one head?  Choices:
A) 1/2
B) 1/4
C) 2/3
D) 3/4
E) 5/7
S = {HH, HT, TH, TT}   E = event of getting at most one head   E = {TT, HT, TH}   P(E) = 3/4   Answer is 3/4
<result>D</result>
Two unbiased coins are tossed. What is the probability of getting at most one head?