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: a searchlight on top of the watchtower makes 4 revolutions per minute . what is the probability that a man appearing near the tower will stay in the dark for at least 12 seconds ? 
Options: a ) 1 / 2 , b ) 2 / 3 , c ) 1 / 3 , d ) 1 / 4 , e ) 1 / 5

Ex Output:
e


Ex Input:
Problem: train a leaves the station traveling at 30 miles per hour . two hours later train в leaves the same station traveling in the same direction at 36 miles per hour . how many miles from the station was train a overtaken by train b ? 
Options: a ) 320 , b ) 360 , c ) 400 , d ) 440 , e ) 480

Ex Output:
b


Ex Input:
Problem: a can do a work in 9 days and b can do the same work in 18 days . if they work together , in how many days will they complete the work ? 
Options: a ) 6 days , b ) 7 days , c ) 5 days , d ) 3 days , e ) 2 days

Ex Output:

a