8. In the plane region $\{(x, y)|| x| \leq 1, | y | \leq 1\}$, it is always true that $a x - 2 b y \leq 2$. Then the area of the plane region formed by the moving point $P(a, b)$ is
A. 4
B. 8
C. 16
D. 32
The plane region $\{(x, y)|| x| \leq 1, | y | \leq 1\}$ has four boundary points $(-1,-1),(-1, 1),(1,-1),(1,1)$ that satisfy $a x - 2 b y \leq 2$, which means
$$
a + 2 b \leq 2, a - 2 b \leq 2, -a - 2 b \leq 2, -a + 2 b \leq 2
$$

From this, the area of the plane region formed by the moving point $P(a, b)$ is calculated to be 4. The correct answer is $\mathrm{A}$.