Answer :
and 
Greatest common factor of 
If we are able to factor out
from each option then that would be our answer.
Lets check with each options
(a)
, we cannot take out 5.
(b)
, We can take out common factor and it can be written as 
(c)
, we cannot take out n^2 because we have only 'n'
(d)
, We can take out common factor and it can be written as 
(e)
, we cannot take out 5 because we have 24
So answer is (b) and (d)