Compute the derivative $of$ the function

$f(x)=\frac{1}{\sqrt[\phantom{2}]{4x^2-5}}$

Select one:

$a.-\frac{4}{4x^2-5}$

$b.-\frac{4x}{(4x^2-5)\sqrt[\phantom{2}]{?}4x^2-5}$

$c.-\frac{1}{\sqrt[\phantom{2}]{?}(4x^2-5{)}^3}$

$d.-\frac{1}{2\sqrt[\phantom{2}]{4x^2-5}}$