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: what is the angle between the minute hand and the hour hand when the time is 1540 hours ? 
Options: a ) 150 , b ) 160 , c ) 140 , d ) 130 , e ) none

Ex Output:
d


Ex Input:
Problem: calculate how many days it will take for 8 boys to paint a 50 m long wall if 6 boys can paint a 60 m long wall in 5 days , 
Options: a ) 4.13 days , b ) 3.13 days , c ) 513 days , d ) 9.13 days , e ) 2 days

Ex Output:
b


Ex Input:
Problem: mary passed a certain gas station on a highway while traveling west at a constant speed of 40 miles per hour . then , 15 minutes later , paul passed the same gas station while traveling west at a constant speed of 60 miles per hour . if both drivers maintained their speeds and both remained on the highway for at least 2 hours , how long after he passed the gas station did paul catch up with mary ? 
Options: a ) 1 / 2 , b ) 2 , c ) 1 , d ) 4 , e ) 5

Ex Output:

a