For each of the following languages state whether it is regular or not. If Li is regular, prove it by drawing a DFA or NFA (your choice) that recognizes it. If the language is not regular, give an argument (in plain language) why there is no DFA or NFA that can recognize it:
(a) [4 marks] Lb = {w ∈ {0, 1}* : w represented as a binary integer is a power of 4}
(b) [4 marks] La = {wwa^n : w ∈ {a, b}, n > 0}
(c) [4 marks] Lc = {wxa : w, x ∈ {a, b}*}
(d) [4 marks] Ld = {wwa : w, x ∈ {a, b}*}