What characterizes the fourth stage of first-language acquisition?

The fourth stage of first-language acquisition, often referred to as the "Telegraphic Speech" stage, is characterized by children's ability to express more complex thoughts and ideas using sentence structures that rely on lexical rather than functional morphemes. During this stage, typically occurring around 24 to 30 months of age, children begin to form multi-word sentences that convey meaning through the use of primarily content words, such as nouns and main verbs, while often omitting grammatical elements that are considered less essential for conveying their message, like articles or prepositions.

This approach allows children to communicate effectively while still developing their understanding of syntax and the nuances of language. They may create phrases such as "want cookie" or "go park," which illustrate their ability to combine words while still prioritizing the most meaningful components of their speech. This stage marks a significant transition toward more complex and grammatically rich language use as children gradually incorporate more of these functional morphemes into their speech.

The other options reflect earlier or less advanced stages of language development, where children may still be focusing on basic vocabulary or the imitation of language rather than independently constructing sentences with the understanding of their structure.