In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: cost is expressed by the formula tb ^ 4 . if b is doubled , the new cost is what percent of the original cost ?
Options: a ) 200 , b ) 600 , c ) 800 , d ) 1600 , e ) 50
Example Output: d

Example Input: Problem: the sum of ages of 5 children born at the intervals of 3 years each is 80 years . what is the age of the youngest child ?
Options: a ) 3 years , b ) 4 years , c ) 6 years , d ) 7 years , e ) 10 years
Example Output: e

Example Input: Problem: on sunday , bill ran 4 more miles than he ran on saturday . julia did not run on saturday , but she ran twice the number of miles on sunday that bill ran on sunday . if bill and julia ran a total of 28 miles on saturday and sunday , how many miles did bill run on sunday ?
Options: a ) 5 , b ) 6 , c ) 7 , d ) 8 , e ) 9
Example Output:
d