1. Define the set operation:
$$
A \otimes B=\{z \mid z=x y, x \in A, y \in B\} \text {. }
$$

Let $A=\{2,0\}, B=\{0,8\}$. Then the sum of all elements in the set $A \otimes B$ is ( ).
(A) 16
(B) 18
(C) 20
(D) 22
-1. A.
The elements of the set $A \otimes B$ are
$$
\begin{array}{l}
z_{1}=2 \times 0=0, z_{2}=2 \times 8=16, \\
z_{3}=0 \times 0=0, z_{4}=0 \times 8=0 .
\end{array}
$$

Therefore, the sum of all elements in the set $A \otimes B$ is 16.