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: if 20 typists can type 48 letters in 20 minutes , then how many letters will 30 typists working at the same rate complete in 1 hour ?
Options: a ) 63 , b ) 72 , c ) 144 , d ) 216 , e ) 400

Ex Output:
d

Ex Input:
Problem: the radius of a semi circle is 70 cm then its perimeter is ?
Options: a ) 32.8 , b ) 32.4 , c ) 360 , d ) 32.2 , e ) 32.9

Ex Output:
c

Ex Input:
Problem: a 230 m long train running at the speed of 120 km / hr crosses another train running in opposite direction at the speed of 80 km / hr in 9 sec . what is the length of the other train ?
Options: a ) 230 , b ) 270 , c ) 260 , d ) 256 , e ) 298

Ex Output:
b