Question

Can someone please help me with this one question
I think the answer is either (C) or (D) but not sure

Answer 1

f(x) + g(x) = -3x^4 - 2x^3 + 3x^2 + 3x^4 - 4x^3 + x^2
f(x) + g(x) = -6x^3 + 4x^2

answer is B

 -6x^3 + 4x^2