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'.

[Q]: Problem: if n is a natural number , then ( 6 n ^ 2 + 6 n ) is always divisible by 
Options: a ) 6 only , b ) 6 and 12 both , c ) 12 only , d ) 18 only , e ) 12 and 18 both
[A]: b


[Q]: Problem: 5 drainage pipes , each draining water from a pool at the same constant rate , together can drain a certain pool in 16 days . how many additional pipes , each draining water at the same constant rate , will be needed to drain the pool in 4 days ? 
Options: a ) 6 , b ) 9 , c ) 10 , d ) 12 , e ) 15
[A]: e


[Q]: Problem: the average of first five multiples of 7 is 
Options: a ) 21 , b ) 6 , c ) 9 , d ) 12 , e ) 15
[A]:
a