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'.

Input: Consider Input: Problem: five bells commence tolling together and toll at intervals of 2 , 4 , 6 , 8 10 seconds respectively . in 20 minutes , how many times do they toll together ? 
Options: a ) 11 , b ) 10 , c ) 15 , d ) 16 , e ) 17

Output: a


Input: Consider Input: Problem: today mary ’ s father is 4 times as old as mary . 3 years ago , he was 5 times as old . how old is mary today ? 
Options: a ) 6 , b ) 8 , c ) 10 , d ) 12 , e ) 14

Output: d


Input: Consider Input: Problem: in a dairy farm , 20 cows eat 20 bags of husk in 20 days . in how many days one cow will eat one bag of husk ? 
Options: a ) 1 , b ) 40 , c ) 20 , d ) 26 , e ) 30


Output: c