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: a train 250 m long is running at a speed of 45 km / hr . in what time will it pass a bridge 150 m long ? 
Options: a ) 45 sec , b ) 42 sec , c ) 32 sec , d ) 48 sec , e ) 25 sec

Ex Output:
c


Ex Input:
Problem: how many seconds will a train 250 meters long take to cross a platform 200 meters long if the speed of the train is 90 kmph ? 
Options: a ) 18 sec , b ) 15 sec , c ) 21 sec , d ) 16 sec , e ) 20 sec

Ex Output:
a


Ex Input:
Problem: two spherical balls lie on the ground touching . if one of the balls has a radius of 9 cm , and the point of contact is 10 cm above the ground , what is the radius of the other ball ( in centimeters ) ? 
Options: a ) 50 / 4 , b ) 70 / 6 , c ) 80 / 7 , d ) 90 / 8 , e ) 100 / 9

Ex Output:

d