The answer would actually be A
F(x)=3x^2+4x
G(x)=2x^2-x+1
The two x^2 items are both positive and are added together to be 5x^2
The two x items would be added together to get 3x cause of the -x
Then +1 is just +1
Making the equation 5x^2+3x+1
If we were subtracting you would be absolutely correct, but since we are adding would go the opposite direction.
I hope this helps!