Which of the following problems is undecidable?

1.	Which of the following problems is undecidable?
A.	Deciding if a given context-free grammar is ambiguous
B.	Deciding if a given string is generated by a given context-free grammar
C.	Deciding if the language generated by a given context-free grammar is empty
D.	Deciding if the language generated by a given context-free grammar is finite
Answer» B. Deciding if a given string is generated by a given context-free grammar

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Which of the following problems is undecidable?

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