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: if a tire rotates at 400 revolutions per minute when the car is traveling 72 km / h , what is the circumference of the tire ?
Options: a ) 7 meters , b ) 9 meters , c ) 8 meters , d ) 5 meters , e ) 3 meters

Ex Output:
e

Ex Input:
Problem: express a speed of 46 kmph in meters per second ?
Options: a ) 10.78 mps , b ) 12.78 mps , c ) 97.78 mps , d ) 17.78 mps , e ) 18.78 mps

Ex Output:
b

Ex Input:
Problem: the length of a train and that of a platform are equal . if with a speed of 90 k / hr , the train crosses the platform in one minute , then the length of the train ( in metres ) is :
Options: a ) 400 , b ) 525 , c ) 750 , d ) 850 , e ) none

Ex Output:
c