The grammar whose productions are → if id then → if id then else → id := idis ambiguous becausea) the sentence if a then if b then c:= d has two parse treesb) the left most and right most derivations of the sentence if a then if b then c:= d give rise to different parse treesc) the sentence if a then if b then c:= d else c:= f has more than two parse treesd) the sentence if a then if b then c:= d else c:= f has two parse trees

• A. a
• B. b
• C. c
• D. d