Here L3 is CFL then also L3/y is CFL.
Now l5 is reversal of l4 and REL is closed under reversal.
Eg- a^nb^nc^nd^n after reversal it will still be REL.
So we know REL are closed under intersection so answer is c) Recursive Enumerable Language .
in one word - L3/y is cfl and L5 is recursive enumerable language. the intersection will result in recursive enumerable language.