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: pipes a and b can fill a tank in 3 and 4 hours . pipe c can empty it in 4 hours . if all pipes are opened together , then the tank will be filled in ? 
Options: a ) 3 hr , b ) 1 / 2 hr , c ) 1 hr , d ) 9 / 7 hr , e ) 5 / 3 hr

Ex Output:
a


Ex Input:
Problem: two trains , one from howrah to patna and the other from patna to howrah , start simultaneously . after they meet , the trains reach their destinations after 49 hours and 25 hours respectively . the ratio of their speeds is ? 
Options: a ) 4 : 9 , b ) 5 : 7 , c ) 4 : 5 , d ) 4 : 1 , e ) 4 : 2

Ex Output:
b


Ex Input:
Problem: the cross - section of a cannel is a trapezium in shape . if the cannel is 14 m wide at the top and 4 m wide at the bottom and the area of cross - section is 380 sq m , the depth of cannel is ? 
Options: a ) 39 , b ) 28 , c ) 27 , d ) 42 , e ) 71

Ex Output:

d