Find the intersection of the following sets : $A=\{x : x$ is a natural number and multiple of $3\},B=\{x : x$ is a natural number less than $6\}$

Question

$\begin{array}{1 1}(A)\;\{1,2,3,4,5,6\}&(B)\;\{3,6,9,12.....\}\\(C)\;\{3,6\}&(D)\;\{3\}\end{array} $