3. [12 marks] This question develops your ability to design CFGs. For each of the following languages, give a CFG. Assume the alphabet is = {a, b). Justify your answers briefly. (b) {x | the length of x is odd). 4. [12 marks] This question develops your ability to design PDAs. For parts (a), (b), (c) of question 3 above, give state diagrams of pushdown automata. For each automata, include a brief description of the idea behind its design