the second one is the answer <i think>
[tex]\\ \tt\hookrightarrow (f+g)(x)[/tex]
[tex]\\ \tt\hookrightarrow f(x)+g(x)[/tex]
[tex]\\ \tt\hookrightarrow 4x^2-5x+3x^2+6x-4[/tex]
[tex]\\ \tt\hookrightarrow 7x^2+x-4[/tex]
Option B is correct
