Final answer:
The correct option is a. Cooing.
The illocutionary stage is not part of the language stages described since it is not a term commonly associated with spoken language development in the textbook context.
Step-by-step explanation:
Among the options provided—cooing, babbling, holophrasic speech, and illocutionary stage—the term "illocutionary stage" is not commonly recognized as part of the traditional stages of language development described in typical developmental psychology textbooks.
The stages typically outlined in language development involve the progression from cooing to babbling and eventually to holophrasic speech. Cooing is the early stage where infants produce vowel-like sounds, usually occurring around two to three months. Babbling follows, involving the repetition of consonant-vowel combinations, usually emerging around six months. Holophrasic speech is a stage around 12 months when a child begins to use single words to convey whole thoughts or ideas.
The term "illocutionary stage" is not a standard part of this sequence. Instead, illocutionary acts are more commonly associated with speech act theory in linguistics, referring to the speaker's intention in producing an utterance (e.g., making a request, giving a command). It's a concept more related to the functions and intentions of speech rather than a distinct stage in early language development.
In summary, the illocutionary stage is not typically recognized in the conventional stages of infant language development, which focus on cooing, babbling, and holophrasic speech as key milestones in the progression toward fully developed spoken language.