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)