Write the Set in Set-Builder Notation $\{ 9,12,15,18 , \ldots , 39 \}$

Write the set in set-builder notation.
- $\{ 9,12,15,18 , \ldots , 39 \}$

A) $\{ x \mid x$ is a multiple of 3 between 6 and $42 \}$
B) $\{ x \mid x$ is a multiple of 3 greater than $9 \}$
C) $\{ x \mid x$ is a multiple of $3 \}$
D) $\{ x \mid x$ is a multiple of 3 between 9 and $39 \}$