In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Ex Input:
Problem: the curved surface of a sphere is 64 π cm 2 . find its radius ? 
Options: ['a ) 8', 'b ) 3', 'c ) 4', 'd ) 9', 'e ) 7']

Ex Output:
c


Ex Input:
Problem: a and b runs around a circular track . a beats b by one round or 10 minutes . in this race , they had completed 4 rounds . if the race was only of one round , find the a ' s time over the course : 
Options: ['a ) 8.5 min', 'b ) 7.5 min', 'c ) 1.5 min', 'd ) 9.5 min', 'e ) 4.5 min']

Ex Output:
b


Ex Input:
Problem: a and b are two multiples of 14 , and q is the set of consecutive integers between a and b , inclusive . if q contains 11 multiples of 14 , how many multiples of 7 are there in q ? 
Options: a ) 19 , b ) 20 , c ) 21 , d ) 22 , e ) 23

Ex Output:

c