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'.

Ex Input:
Problem: a tree is 12 m tall and casts an an 8 m long shadow . at the same time , a flag pole caste a 100 m long shadow . how long is the flag pole ? 
Options: a ) 150 m , b ) 200 m , c ) 125 m , d ) 115 m , e ) none

Ex Output:
a


Ex Input:
Problem: calculate the circumference of a circular field whose radius is 8 centimeters . 
Options: a ) 17 π cm , b ) 18 π cm , c ) 1 π cm , d ) 16 π cm , e ) 6 π cm

Ex Output:
d


Ex Input:
Problem: 600 men have provisions for 20 days . if 200 more men join them , for how many days will the provisions last now ? 
Options: a ) 15 , b ) 11 , c ) 10 , d ) 8 , e ) 7

Ex Output:

a