What cultural feature leads to a language being classified as endangered or dying?

(1 point)
States that previously listed the language as their official language have become part of a country using a different language.
Parents who speak the language are unable or unwilling to teach it to their own children.
States that previously listed the language as their institutional language have ceased to exist as independent states.
Researchers determine that the language's working vocabulary is too small to justify treating it as a language.
Researchers determine that the language has no literary tradition of poetry and narrative

All of the options listed can potentially contribute to a language being classified as endangered or dying. However, the option that specifically relates to the cultural feature leading to this classification is: Parents who speak the language are unable or unwilling to teach it to their own children.