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: lionel left his house and walked towards walt ' s house , 48 miles away . two hours later , walt left his house and ran towards lionel ' s house . if lionel ' s speed was 3 miles per hour and walt ' s 3 miles per hour , how many miles had lionel walked when he met walt ? 
Options: a ) 12 , b ) 16 , c ) 20 , d ) 27 , e ) 28
Example Output: d

Example Input: Problem: stacy has a 81 page history paper due in 3 days . how many pages per day would she have to write to finish on time ? 
Options: a ) 9 , b ) 27 , c ) 10 , d ) 8.5 , e ) 6
Example Output: b

Example Input: Problem: a hollow iron pipe is 42 cm long and its external diameter is 8 cm . if the thickness of the pipe is 1 cm and iron weighs 3 g / cm 3 , then the weight of the pipe is : 
Options: a ) 2.172 kg , b ) 2.272 kg , c ) 2.282 kg , d ) 2.992 kg , e ) 2.772 kg
Example Output:
e