given f(x)=-6x-1 and g(x)=x^3,choose the expression for (f g)(x)
A.-18x^3-3
B.-6x^3-1
c.-6x^3-1x^3
D.(-6x-1)^3
A.-18x^3-3
B.-6x^3-1
c.-6x^3-1x^3
D.(-6x-1)^3