Which of the following is true?

2002

Which of the following is true?

  1. A.

    The complement of a recursive language is recursive.

  2. B.

    The complement of a recursively enumerable language is recursively enumerable.

  3. C.

    The complement of a recursive language is either recursive or recursively enumerable.

  4. D.

    The complement of a context-free language is context-free.

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Correct answer: A

Recursive languages are closed under complementation, meaning if a language is recursive, its complement is also recursive. Recursively enumerable and context-free languages are not necessarily closed under this operation, making the statement about recursive languages the only valid choice among standard language classes.

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