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: there are two tanks a & b with same capacity of 20 litres . if the water inflow rate ( speed ) in tank a is 2 litres per hour & in tank b is 4 litres per hour . how much longer tank a takes to fill than tank b ? 
Options: a ) 4 hours , b ) 5 hours , c ) 3 hours , d ) 2 hours , e ) 1 hour
Example Output: b

Example Input: Problem: aaron will jog from home at 2 miles per hour and then walk back home by the same route at 4 miles per hour . how many miles from home can aaron jog so that he spends a total of 3 hours jogging and walking ? 
Options: a ) 5 , b ) 7 , c ) 3 , d ) 9 , e ) 10
Example Output: c

Example Input: Problem: a student completes a 3 part exam as follows . the student completes sections a in 18 minutes and takes an equal time to complete the two remaining sections . what is the ratio of time spent on section c to section a if the total duration is 1 hour ? 
Options: a ) 4 : 3 , b ) 5 : 4 , c ) 6 : 5 , d ) 7 : 6 , e ) 8 : 7
Example Output:
d