Answer:
C
Step-by-step explanation:
The volume of a cube is [tex]s^3[/tex] where s is the side length. The side length here is (x+4) so the volume is [tex](x+4)^3[/tex]. This multiplies out to be
[tex](x+4)(x+4)(x+4)\\(x^2+8x+16)(x+4)\\x^3+8x^2+16x+4x^2+32x+64\\x^3+12x^2+48x+64[/tex]