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'.

Input: Consider Input: Problem: a and b can do a piece of work in 8 days . with the help of c they finish the work in 4 days . c alone can do that piece of work in ? 
Options: a ) 40 days , b ) 20 days , c ) 8 days , d ) 60 days , e ) 40 days

Output: c


Input: Consider Input: Problem: how many shots of 1 cm radius can be prepared from a sphere of 4 cm radius ? 
Options: a ) 33 , b ) 88 , c ) 27 , d ) 64 , e ) 99

Output: d


Input: Consider Input: Problem: the length of the bridge , which a train 140 meters long and travelling at 45 km / hr can cross in 30 seconds , is ? 
Options: a ) 328 , b ) 279 , c ) 235 , d ) 288 , e ) 211


Output: c