Which of the following are undecidable?
$P1$: The language generated by some CFG contains any words of length less than some given number $n$.
$P2$: Let $L1$ be CFL and $L2$ be regular, to determine whether $L1$ and $L2$ have common elements
$P3$: Any given CFG is ambiguous or not.
$P4$: For any given CFG $G$, to determine whether epsilon belongs to $L(G)$
- $P2$ only
- $P1$ and $P2$ only
- $P2$ and $P3$ only
- $P3$ only