Answer:
option (B) is correct.
Mystery term has to be 
Step-by-step explanation:
Given :
is the GCF of the polynomial 
We have to find the mystery term '?'
GCF stands for greatest common factor. GCF is the highest common factor that can divide all the given terms.
Here,
is the GCF of the polynomial 
For unknown term , we have two conditions,
1) it has to be multiple of 4
2) it must have
as a factor.
So out of given options only
is a term which is both multiple of 4 and has
as a factor.
Thus, Mystery term has to be 
Thus, option (B) is correct.