Which of the following equations represents a quadratic function?

Select one:
A. x(3x^2−x)=4x^2
B. x^3−x^2−x−1=0
C. −6x−5=−8x^2
D. 8−9(x−1)=3x


Answer :

I believe it’s c correct me if I’m wrong
It is B because all quadratic equations are always equal to 0 in the start