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: the speed of a boat in still water is 15 km / hr and the rate of the current is 3 km / hr . the distance travelled downstream in 12 minutes is
Options: a ) 1.2 km , b ) 1.8 km , c ) 2.4 km , d ) 3.6 km , e ) none

Ex Output:
d

Ex Input:
Problem: it takes joey the postman 1 hours to run a 7 mile long route every day . he delivers packages and then returns to the post office along the same path . if the average speed of the round trip is 8 mile / hour , what is the speed with which joey returns ?
Options: a ) 11 , b ) 12 , c ) 13 , d ) 8 , e ) 15

Ex Output:
d

Ex Input:
Problem: the length of the bridge , which a train 160 meters long and travelling at 45 km / hr can cross in 30 seconds , is :
Options: a ) 230 , b ) 244 , c ) 245 , d ) 215 , e ) 236

Ex Output:
d