How can the decision algorithm be constructed for deciding whether context-free language $L$ is finite?

$(a)$ By constructing redundant CFG $G$ in CNF generating language $L$

$(b)$ By constructing non-redundant CFG $G$ in CNF generating language $L$

$(c)$ By constructing non-redundant CFG $G$ in CNF generating language $L-{\Lambda}$, where $\Lambda$ stands for null

Which of the following is correct?

To decide whether a context-free language is finite or infinite, we can convert the CFG into a non-redundant CFG in CNF.

Usually, the CNF grammar is considered for $L-{\Lambda}$.

After converting into CNF, we check whether there is any recursive derivation or cycle among variables.

If such a recursive structure exists, then the language is infinite.

If no such recursive structure exists, then the language is finite.

So, the correct construction is given in statement $(c)$.