$71$Q $]$ Let $f(x)=x^{2}2x.$ Which of the following is equal to $f^{\text{'}}(x)?$

$($A$)\underset{h0}{lim}\frac{(xh{)}^{2}2x-x^2-2x}{h}$

$($B$)\underset{h0}{lim}\frac{(xh{)}^{2}2(xh)-x^2-2x}{h}$

$($C$)\underset{h0}{lim}\frac{(xh{)}^{2}2(xh)-x^{2}2x}{h}$

$($D$)\underset{h0}{lim}\frac{x^{2}2xh-x^2-2x}{h}$

$($E$)\underset{h0}{lim}\frac{(xh{)}^{2}3x-x^2-3x}{h}$