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'.

Example Input: Problem: r is the set of positive even integers less than 20 , and s is the set of the squares of the integers in r . how many elements does the intersection of r and s contain ? 
Options: ['a ) none', 'b ) two', 'c ) three', 'd ) five', 'e ) seven']
Example Output: c

Example Input: Problem: the speed of a boat in still water in 42 km / hr and the rate of current is 6 km / hr . the distance travelled downstream in 44 minutes is : 
Options: a ) 86.6 km , b ) 46.6 km , c ) 35.2 km , d ) 35.6 km , e ) 26.6 km
Example Output: c

Example Input: Problem: the speed of a train is 72 kmph . what is the distance covered by it in 20 minutes ? 
Options: a ) 20 kmph , b ) 28 kmph , c ) 25 kmph , d ) 22 kmph , e ) 24 kmph
Example Output:
e