okay CFL s are closed under Union
so 1 is correct
option 2: L1' is not CFL as it is not closed under complementation
option 3 is nothing but intersection with regular language which is CFL
3 is correct so
4 is not correct as cfl is not closed under intersection
so from this i get 1,2,3 correct but that is not in option i think your option 2 will be a different..
so 1 and 3 correct