Chọn phương án B.

\(\begin{aligned}
P&=\left(\dfrac{1}{16}\right)^{-0,75}+(0,25)^{-\tfrac{5}{2}}\\
&=\left(2^{-4}\right)^{-\tfrac{3}{4}}+\left(2^{-2}\right)^{-\tfrac{5}{2}}\\
&=2^{(-4)\cdot\left(-\tfrac{3}{4}\right)}+2^{(-2)\cdot\left(-\tfrac{5}{2}\right)}\\
&=2^3+2^5=8+32=40.
\end{aligned}\)