Two unbiased coin are tossed .What is the probability of getting at most one head?

Answer: Option C

Sample space (All [possible outcomes)S=(HH, HT, TH, TT)
Event(required outcomes) = (TT, HT, TH)
$$\begin{array}{rl}& \text{p}\left(\text{E}\right)=\frac{\text{n}\left(\text{E}\right)}{\text{n}\left(\text{S}\right)}\\ & =\frac{3}{4}\end{array}$$