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: in a 80 meters race a beats b by 56 m or 7 seconds . a ' s time over the course is : 
Options: a ) 3 seconds , b ) 12 seconds , c ) 10 seconds , d ) 18 seconds , e ) 28 seconds
Example Output: a

Example Input: Problem: find the area of trapezium whose parallel sides are 20 cm and 18 cm long , and the distance between them is 10 cm . 
Options: a ) 287 cm 2 , b ) 190 cm 2 , c ) 180 cm 2 , d ) 785 cm 2 , e ) 295 cm 2
Example Output: b

Example Input: Problem: a person walks from one end to the other of a 90 - meter long moving walkway at a constant rate in 30 seconds , assisted by the walkway . when this person reaches the end , they reverse direction and continue walking with the same speed , but this time it takes 120 seconds because the person is traveling against the direction of the moving walkway . if the walkway were to stop moving , how many seconds would it take this person to walk from one end of the walkway to the other ? 
Options: a ) 36 , b ) 42 , c ) 48 , d ) 54 , e ) 60
Example Output:
c