The total number of ways to choose any subset of the 5 options =25=32 These 32 subsets include choosing 2,3,4 or 5 options. But choosing options 0 and 1 are not allowed. Now, subsets with 0 options =‌5C0=‌
5!
0!5!
=1 Subsets with 1 options =‌5C1=‌
5!
1!4!
=5 So, total subsets with options 0 and 1 =1+5=6 Thus, the number of ways in which the student can answer that questions =32−6=26