Answer:
a.  
  
Step-by-step explanation:   
We are asked to find the probability of getting 3 heads on 4 flips. 

Since we know that flipping a fair coin has 2 equally likely possible outcomes, so flipping four coins will have  possible outcomes.
 possible outcomes.
Sample space of possible outcomes.
HHHH, HHHT, HHTH, HHTT, HTHH, HTHT, HTTH, HTTT,
 THHH, THHT, THTH,THTT, TTHH, TTHT, TTTH, TTTT.
We can see that there are 4 favorable outcomes of getting heads.
 
 
 
 
Therefore, the probability of getting 3 heads on 4 coins will be  and option a is the correct choice.
 and option a is the correct choice.