Let L be a given context-free language over the alphabet {a, b}. Construct L1, L2 as follows.
Let L1 = L − {xyx | x, y ∈ {a, b}∗},
and L2 = L·L. Then,
(A) Both L1 and L2 are regular.
B) Both L1 and L2 are context free but not necessarily regular.
(C) L1 is regular and L2 is context free.
(D) L1 and L2 both may not be context free