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'.

Example Input: Problem: the length of the longest tape in cm which can be used to measure exactly , the length 7 m ; 3 m 85 cm ; and 12 m 95 cm is : 
Options: a ) 37 , b ) 35 , c ) 34 , d ) 36 , e ) 38
Example Output: b

Example Input: Problem: three pipes of same capacity can fill a tank in 8 hours . if there are only two pipes of same capacity , the tank can be filled in . 
Options: a ) 11 hours , b ) 12 hours , c ) 15 hours , d ) 16 hours , e ) 17 hours
Example Output: b

Example Input: Problem: a walks at 30 kmph and 30 hours after his start , b cycles after him at 48 kmph . how far from the start does b catch up with a ? 
Options: a ) 1200 km , b ) 1500 km , c ) 2000 km , d ) 2400 km , e ) 3600 km
Example Output:
d