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: ajay can walk 6 km in 1 hour . in how many hours he can walk 70 km ?
Options: a ) 5 hrs , b ) 11.6 hrs , c ) 15.6 hrs , d ) 20.1 hrs , e ) 30 hrs

Ex Output:
b

Ex Input:
Problem: in a 500 m race , the ratio of the speeds of two contestants a and b is 3 : 4 . a has a start of 155 m . then , a wins by :
Options: a ) 60 m , b ) 20 m , c ) 40 m , d ) 20 m , e ) 23 m

Ex Output:
c

Ex Input:
Problem: two pipes can fill a tank in 20 minutes and 15 minutes . an outlet pipe can empty the tank in 45 minutes . if all the pipes are opened when the tank is empty , then how many minutes will it take to fill the tank ?
Options: a ) 5 minutes , b ) 17 minutes , c ) 15 minutes , d ) 10 minutes , e ) 12 minutes

Ex Output:
a