Write the Set in Set-Builder Notation $\{ x \mid x$ Is the Natural Number

Multiple Choice

Write the set in set-builder notation.
-{7}

A) $\{ x \mid x$ is the natural number $7 \}$
B) $\{ x$ is a constant $\}$
C) $\{ x \}$
D) $\{ x \mid x$ is a natural number $\}$