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 edges of a cuboid are 4 cm , 4 cm and 6 cm . find the volume of the cuboid ? 
Options: a ) 90 , b ) 60 , c ) 96 , d ) 80 , e ) 72
Example Output: c

Example Input: Problem: a river boat leaves silver town and travels upstream to gold town at an average speed of 3 kilometers per hour . it returns by the same route at an average speed of 7 kilometers per hour . what is the average speed for the round - trip in kilometers per hour ? 
Options: a ) 4.2 , b ) 7.1 , c ) 7.2 , d ) 7.5 , e ) 8.0
Example Output: a

Example Input: Problem: john can complete a given task in 20 days . jane will take only 10 days to complete the same task . john and jane set out to complete the task by beginning to work together . however , jane was indisposed 5 days before the work got over . in how many days did the work get over from the time john and jane started to work on it together ? 
Options: a ) 8 , b ) 10 , c ) 12 , d ) 16 , e ) 20
Example Output:
b