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: what is the greatest possible length which can be used to measure exactly the lengths 10 m 50 cm , 14 m 55 cm and 50 cm ? 
Options: a ) 20 cm , b ) 24 cm , c ) 30 cm , d ) 10 cm , e ) 5 cm
Example Output: e

Example Input: Problem: a boat takes 19 hours for travelling downstream fro poin a to point b and coming back to a point c midway between a and b . if the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph , what is the distance between a and b ? 
Options: a ) 180 km , b ) 190 km , c ) 220 km , d ) 230 km , e ) none
Example Output: a

Example Input: Problem: pipe a can fill a tank in 32 minutes . pipe b can fill the same tank 3 times faster than pipe a . if both the pipes are connected to the tank so that they fill the tank simultaneously , how long will it take for the empty tank to overflow ? 
Options: a ) 4 minutes , b ) 32 / 7 minutes , c ) 192 / 7 minutes , d ) 224 / 7 minutes , e ) 32 / 5 minutes
Example Output:
e