Which of the following is true?

Finite languages are closed under union.

Given a finite language $L$ it follows that $\frac{{}^{**}}{\frac{?}{?}}L$ is finite.

Given a finite language $L$ and a finite language $K$ such that LsubeK it follows that $\frac{K}{\frac{?}{?}}L$ is finite.

$($a$)$ and $($c$).$

All of the above.