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: if 21 lines are drawn in a plane such that no two of them are parallel and no three are concurrent , then in how many points do they intersect ? 
Options: a ) 150 , b ) 170 , c ) 190 , d ) 210 , e ) 230
Example Output: d

Example 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
Example Output: c

Example Input: Problem: two trains 111 meters and 165 meters in length respectively are running in opposite directions , one at the rate of 100 km and the other at the rate of 120 kmph . in what time will they be completely clear of each other from the moment they meet ? 
Options: a ) 4.85 , b ) 7.85 , c ) 4.51 , d ) 5.85 , e ) 6.15
Example Output:
c