15 The inverse function of $y=\left(\log _{2} \frac{1}{2}\right)\left(\log _{2} x\right)$ is
A. $y=\log _{2} x$
B. $y=2^{x}$
C. $y=2^{\frac{1}{x}}$
D. $y=\left(\frac{1}{2}\right)^{x}$
15 D. $y=-\log _{2} x, x=2^{-y}$. So the inverse function of $y=-\log _{2} x$ is $y=2^{-x}$.