For each of the following languages, say whether it is context-free. If so, write a CFG or draw a PDA (non-mathematically) that generates the language. If not, prove it using the pumping lemma and/or closure properties for CFLs.

(a) L = {a^n² | n 0}. (a to the power n squared)

(b) L = {a^mbⁿc^(mn) | m n}

(c) L = {a^m bⁿ c^mn | m, n 0}

(d) L = {aⁿ bⁿ c^m | m > n}