3. Consider the following CFG with alphabet (a, b) and start variable S: SAB AaAa B-Bb Az Both a. [4 marks] What is the shortest string in the language of the grammar excluding the empty string? b. [4 marks] Draw the derivation tree for the string in (a). I C. [4 marks] Explain whether this grammar is ambiguous or not? d. [4 marks) Describe in English the language generated by the grammar. e. [4 marks) Explain why this CFG can or cannot generate a regular language. (20 marks)