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: two trains are moving in opposite directions with speed of 90 km / hr and 90 km / hr respectively . their lengths are 1.10 km and 0.9 km respectively . the slower train cross the faster train in - - - seconds 
Options: a ) 56 , b ) 40 , c ) 47 , d ) 26 , e ) 25

Ex Output:
b


Ex Input:
Problem: a tiger is chasing its prey at a constant speed . it entire body passes a blade of grass in 1 second . it then runs above a fallen tree trunk that is 20 meters long in 5 seconds . what is the length of the tiger ? 
Options: a ) 6 m , b ) 5 m , c ) 4 m , d ) 3 m , e ) none of the above

Ex Output:
b


Ex Input:
Problem: two spherical balls lie on the ground touching . if one of the balls has a radius of 3 cm , and the point of contact is 5 cm above the ground , what is the radius of the other ball ? 
Options: a ) 3 cm , b ) 9 cm , c ) 12 cm , d ) 15 cm , e ) none of the these

Ex Output:

d