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 4 xz + yw = 3 and xw + yz = 6 , what is the value of the expression ( 2 x + y ) ( 2 z + w ) ? 
Options: a ) 9 . , b ) 12 . , c ) 15 . , d ) 16 , e ) 18 .

Output: c


Input: Consider Input: Problem: when average age of 22 members are 0 , how many members greater than 0 ? 
Options: a ) 17 , b ) 21 , c ) 22 , d ) 24 , e ) 25

Output: b


Input: Consider Input: Problem: simplify : 500 x 500 - 200 x 200 
Options: a ) 761200 , b ) 761400 , c ) 761800 , d ) 210000 , e ) none of them


Output: d