Q. 24 Which of the following problems are decidable?
1. Does a given program ever produce an output?
2. If L is a context-free language, then, is L also context-free?
3. If L is a regular language, then, is L also regular?
4. If L is a recursive language, then, is L also recursive?
(A) 1, 2, 3, 4
(B) 1, 2
(C) 2, 3, 4
(D) 3, 4
Answer: (D)
Explanation:
