Which rational expression is undefined when x is equal to 0 ?
A
the fraction with numerator 6 x squared and denominator 9 x minus 3B
the fraction with numerator 4 x minus 8 and denominator negative 2 x squaredC
the fraction with numerator 5 x squared minus 4 and denominator 3 x minus 3D
the fraction with numerator 8 x plus 6 and denominator negative x squared plus 1