List the Elements of the Set $A = \{ x \mid x$

Multiple Choice

List the elements of the set.
-If $A = \{ x \mid x$ is an odd integer $\}$ and $B = \{ x \mid x$ is an even integer $\}$ , list the elements of $A \cup B$ .

A) $\{ x \mid x$ is an integer $\}$
B) $\{ x \mid x$ is an even integer $\}$
C) $\{ 0 \}$
D) { }