Answer:
Given:
• P is the set of integers that are multiples of 3 between 1 and 20.
,
• Q is the set of even natural numbers up to 15.
The elements of P and Q are:
[tex]\begin{gathered} P=\{3,6,9,12,15,18\} \\ Q=\{2,4,6,8,10,12,14\} \end{gathered}[/tex]
The union of P and Q is:
[tex]P\cup Q=\{2,3,4,6,8,9,10,12,14,15,18\}[/tex]
We observe that 5 is not in the union of P and Q, therefore, the set that is NOT a subset of the union of P and Q is:
{3,5,6,12}
The correct choice is A.
