Which of the following terms refers to the functional units of language that compose an individual's verbal repertoire?

The term that best refers to the functional units of language that compose an individual's verbal repertoire is "verbal operants." This concept, originating from the field of Behavior Analysis, refers to the different ways in which individuals use language to communicate. Verbal operants include practices such as manding (requests), tacting (labeling), and intraverbal behavior (conversational responses), among others. Each of these categories reflects a specific functional relationship between the speaker and their environment, illustrating how language serves practical communication needs.

By focusing on verbal operants, practitioners can analyze and enhance an individual's ability to communicate effectively, as these operants directly relate to the functions of language in real-life situations. This understanding is crucial for developing targeted interventions in language acquisition and communication skills.