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: a parking garage rents parking spaces for $ 10 per week or $ 25 per month . how much does a person save in a year by renting by the month rather than by the week ? 
Options: a ) $ 120 , b ) $ 160 , c ) $ 220 , d ) $ 240 , e ) $ 260

Output: a


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: in how many ways can 5 different rings be worn in 4 particular fingers ? ( some fingers may get more than one ring and some may get no rings . ) can somebody explain ? 
Options: a ) 6720 , b ) 7720 , c ) 7820 , d ) 7950 , e ) 8120


Output: a