For this case we have by definition, the GFC of two numbers is given by the largest factor that divides both numbers without leaving residue.
We have the following expression:
and

So, we look for the factors of 3 and 4:
3: 1.3
4: 1, 2, 4
Thus, the GFC of both numbers is "1".
The GFC of both expressions is:

Answer:
p