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 hall 36 m long and 15 m broad is to be paved with stones , each measuring 8 dm by 5 dm . the number of stones required is :
Options: a ) 180 , b ) 1800 , c ) 18 , d ) 18000 , e ) 1350

Ex Output:
e

Ex Input:
Problem: a train is 300 meter long is running at a speed of 35 km / hour . in what time will it pass a bridge of 115 meter length ?
Options: a ) 29 , b ) 23 , c ) 47.119 , d ) 44.586 , e ) 42.686

Ex Output:
e

Ex Input:
Problem: a 600 meter long train crosses a signal post in 60 seconds . how long will it take to cross a 3 kilometer long bridge , at the same speed ?
Options: a ) 4 min , b ) 2 min , c ) 6 min , d ) 9 min , e ) 5 min

Ex Output:
c