Question

Consider the languages L1={0^{i}1^{j}|i != j}, L2={0^{i}1^{j}|i = j}, L3 = {0^{i}1^{j}|i = 2j+1}, L4 = {0^{i}1^{j}|i != 2j}. Which one of the following statements is true?

a) Only L2 is context free
b) Only L2 and L3 are context free
c) Only L1 and L2 are context free
d) All are context free