L1 is regular,L is regular then $ L1\cap L2$ is also a regular because regular is closed under intersection.
https://www.geeksforgeeks.org/closure-properties-of-regular-languages/
it is also closed under union, concatenation, kleen closure, set difference, positive closure, complement, reverse operator, homomorphism, inverse homomorphism etc
if L1 and L2 are regular languages, then each of also $L1\cup L2$ , $L1.L2$ and $L1^{*}$ is regular etc.
option A