3. Consider the following grammar (G1) for simple assignment statements. (The symbols in double quotation marks are terminal symbols.) expr expr "*" expr I ""expr ")" id a) Give a (leftmost) derivation for string A B A - C b) Give a parse tree for string A : B * A-C c) Is the grammar ambiguous or unambiguous? Explain your answer d) Consider the following grammar (G2) id-"A" "B"C". expr- expr "-" id expr " id epr ")