In this task, you need to provide the correct option for a given problem on probability from the provided options.

Problem: two unbiased coins are tossed . find the probability of getting at most one head ? 
Options: a ) 1 / 2 , b ) 3 / 4 , c ) 2 / 5 , d ) 2 / 3 , e ) 1 / 4
b