Parse tree ambiguous or not

Question

If i am wrong please let me correct with giving proper explanation.

Answer 1

Yes, Correct! but a string can not ambiguous. Though given grammar is ambiguous!

A grammar will be called ambiguous if can generate more than one parse tree/Left most derivations/Right most derivations for same string.
One more point to be noticed here is that, in first parse tree, left id*id will be evaluated first while in second parse tree id+id will be evaluated first,

Comments

Means 2&4 both options are correct

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i think 4th is only answer.

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But here in option 2 two parse tree are possible then why not option 2.

please reply...

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As i earlier mentioned in my solution, both parse trees are not same, as in first tree * will be evaluated first and in second tree, + will be evaluated first.