If $A=\{3,5,7,9,11\},B=\{7,9,11,13\},C=\{11,13,15\}$ and $D=\{15,17\}$.Find $A\cap C$

Question

$\begin{array}{1 1}(A)\;\{3,5,7,9,11\}&(B)\;\{11,13,15\}\\(C)\;\phi&(D)\;\{11\}\end{array}$