Help Please!!!!!!

f(x)=5x^2+9x−4

g(x)=−8x^2−3x−4

Find (f+g)(x)

My Options Are...:
a. 3x^2+6x−8
b. −3x^3+6x^2−8x
c. −3x^4+6x^2−8
d. −3x^2+6x−8