Teacher: In this task, you need to provide the correct option for a given problem on probability from the provided options.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Problem: in a throw of a coin find the probability of getting a tail ? 
Options: a ) 1 / 2 , b ) 1 / 3 , c ) 1 / 4 , d ) 2 / 5 , e ) 2 / 7
Solution: a
Reason: "s = { h , t } e = { t } p ( e ) = 1 / 2 answer is a"

Now, solve this instance: Problem: what is the probability of getting exactly 2 heads in a single throw of four fair coins ? 
Options: a ) 1 / 2 , b ) 3 / 4 , c ) 3 / 8 , d ) 3 / 16 , e ) 5 / 16
Student:
c