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: in what time will a train 20 m long cross an electric pole , it its speed be 144 km / hr ? 
Options: a ) 2.5 sec , b ) 2.8 sec , c ) 0.5 sec , d ) 2.3 sec , e ) 1.5 sec
Example Output: c

Example Input: Problem: a certain bacteria colony doubles in size every day for 20 days , at which point it reaches the limit of its habitat and can no longer grow . if two bacteria colonies start growing simultaneously , how many days will it take them to reach the habitat ’ s limit ? 
Options: a ) 6.33 , b ) 7.5 , c ) 10 , d ) 15 , e ) 19
Example Output: e

Example Input: Problem: a and b are two multiples of 14 , and q is the set of consecutive integers between a and b , inclusive . if q contains 13 multiples of 14 , how many multiples of 7 are there in q ? 
Options: a ) 23 , b ) 24 , c ) 25 , d ) 26 , e ) 27
Example Output:
c