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: two cyclist start on a circular track from a given point but in opposite direction with speeds of 7 m / s and 8 m / s . if the circumference of the circle is 630 meters , after what time will they meet at the starting point ? 
Options: a ) 20 sec , b ) 15 sec , c ) 42 sec , d ) 50 sec , e ) 1 min

Ex Output:
c


Ex Input:
Problem: a can finish a work in 12 days and b can do the same work in 15 days . b worked for 10 days and left the job . in how many days , a alone can finish the remaining work ? 
Options: a ) 4 , b ) 5 1 / 2 , c ) 6 , d ) 8 , e ) none of these

Ex Output:
a


Ex Input:
Problem: a can do a job in 15 days and b in 20 days . if they work on it together for 3 days , then the fraction of the work that is left is ? 
Options: a ) 2 / 15 , b ) 8 / 15 , c ) 13 / 20 , d ) 1 / 12 , e ) 6 / 13

Ex Output:

c