1. Given the universal set $U=\mathbf{R}$, the sets
$$
\begin{array}{l}
N=\left\{x \left\lvert\,\left(\frac{1}{2}\right)^{x} \leqslant 1\right.\right\}, \\
M=\left\{x \mid x^{2}-6 x+8 \leqslant 0\right\} .
\end{array}
$$

Then the set represented by the shaded area in Figure 1 is ( ).
(A) $\{x \mid x \leqslant 0\}$
(B) $\{x \mid 2 \leqslant x \leqslant 4\}$
(C) $\{x \mid 04\}$
1. D.
From the problem, we know that the solution sets of sets $N$ and $M$ are $N=\{x \mid x \geqslant 0\}, M=\{x \mid 2 \leqslant x \leqslant 4\}$.
Therefore, the required solution set is $\{x \mid 0 \leqslant x \leqslant 4\}$.