Which of the following are context free language ?

(A) ${w^i x^j y^k z^l \mid i + k = j + l,; i,j,k,l \ge 0}$

(B) ${w^i x^j y^k z^l \mid i = j \text{ and } k = l,; i,j,k,l \ge 0}$

(C) ${w^i x^j y^k z^l \mid i = j = k \text{ and } k \ne l,; i,j,k,l \ge 0}$

(D) ${w^i x^j y^k z^l \mid i = j = k + l,; i,j,k,l \ge 0}$

(E) ${w^i x^j y^k z^l \mid i = j \text{ and } k \ne l,; i,j,k,l \ge 0}$

Choose the correct answer from the options given below :

(A) Condition $ i + k = j + l $ This type of dependency is not context free (requires two independent balances). So not CFL. (B) Conditions $ i = j $ and $ k = l $ Language form $ w^i x^i y^k z^k $ This is context free. (C) Condition $ i = j = k $ This is similar to $ a^n b^n c^n $ which is not context free. (D) Condition $ i = j = k + l $ Single dependency handled by PDA → Context Free. (E) Condition $ i = j $ and $ k \ne l $ Still context free (difference condition allowed). Correct CFL: (D) and (E)