Which verbal operant is characterized by an individual saying what another individual just said?

The verbal operant that involves an individual repeating what another individual has just said is known as an echoic. This type of response is characterized by the individual producing verbal behavior that closely matches the verbal stimulus they heard. Echoics are often used in teaching language and communication skills, as they help in developing the ability to imitate sounds and words accurately.

In this case, the focus on repeating speech distinguishes echoics from other verbal operants. For instance, intraverbals involve responses that are related to the conversational flow but do not require direct repetition of what was said. Mands involve requests or demands that are driven by a need or desire, while tacts involve labeling or identifying objects, actions, or events based on the speaker's direct experience.

Thus, the nature of echoics lies specifically in verbal imitation, making it the correct choice for this question.