Find the error in the following work.

$D_x(\frac{2x5}{x^2-1})=\frac{(2x5)(2x)-(x^2-1)2}{(x^2-1{)}^2}$

$=\frac{4x^{2}10x-2x^{2}2}{(x^2-1{)}^2}$

$=\frac{2x^{2}10x2}{(x^2-1{)}^2}$

Choose the correct answer below.

A$.$ In the first step, the numerator should be $(x^2-1)2-(2x5)(2x).$

B$.$ In the last step, the numerator should be $2x^2-10x2.$

C$.$ In the first stop, the numerator should be $(x^2-1)(2x5)-(2x)2$

D$.$ In all three steps, the denominator should be $(2x5{)}^2.$