What is the meaning of the verb 'jabber'?

The meaning of the verb 'jabber' refers specifically to talking rapidly or in a way that is difficult to understand, often characterized by a lack of clarity or coherence. This aligns well with the answer choice indicating rapid and unintelligible speech. When someone is jabbering, they may be speaking so quickly that their words become a blur, making it hard for listeners to follow or grasp what is being communicated. This term is often used to describe conversations where the speaker is excited or agitated and, as a result, their speech becomes less articulate.

The other meanings provided in the choices do not connect with the essence of 'jabber.' For instance, speaking clearly or pausing in speech would imply a controlled or thoughtful manner of talking, which is the opposite of what 'jabber' conveys. Writing extensively also does not relate to speech patterns. Therefore, the correct response captures the essence of the word and its common usage in the English language.