If $A=\{1,2,3,4\},B=\{3,4,5,6\},C=\{5,6,7,8\}$ and $D=\{7,8,9,10\}$ Find $A\cup C$

Question

$\begin{array}{1 1}(A)\;\{1,2,3,4,5,6,7,8\}\\(B)\;\{1,2,3,4,5\}\\(C)\;\{1,3,5,6\}\\(D)\;\{2,4,6,8\}\end{array} $