Which of the following decision problems are undecidable?
Correct Answer: $C$
@Ankit Meena We are talking about language produced by CFG, by default CFL (because DCFL is also CFL). For CFL, equivalence is undecidable.
Option C will be right option
Since equality problem is always undecidable in the case of CFL,CSL,RL and RE.
Similarly Emptiness proble is Undecidable in the case of TM,CSL,RL