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'.

Input: Consider Input: Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab . 
Options: a ) 9 , b ) 2 , c ) 3 , d ) 7 , e ) 12

Output: c


Input: Consider Input: Problem: if a and b are positive numbers , and a ^ 3 + b ^ 3 = 100 , then the greatest possible value of a is between : 
Options: a ) 0 and 3 , b ) 3 and 4 , c ) 4 and 5 , d ) 5 and 7 , e ) 7 and 9

Output: c


Input: Consider Input: Problem: evaluate : 6402.5 + 640.25 + 64.025 + 6.4025 + 0.64025 
Options: a ) 6819.59775 , b ) 6981.59775 , c ) 6918.59775 , d ) 7113.81775 , e ) 6891.59775


Output: d