What is the likely diagnosis for Jeffery, who exhibits rapid speech and frequent fillers such as "um" or "like"?

The indication that Jeffery exhibits rapid speech and frequent fillers such as "um" or "like" aligns closely with the characteristics of cluttering. Cluttering is a fluency disorder that involves a rapid or irregular speech rate, which can lead to unclear speech patterns. Individuals who clutter may also struggle to organize their thoughts, often resulting in the use of fillers to pause and collect their thoughts. This explains the notable presence of fillers in Jeffery's speech.

In contrast, developmental stuttering typically features repetitions or prolongations of sounds and syllables rather than rapid speech and fillers. Advanced stuttering may involve more complex characteristics of stuttered speech, often including tension and avoidance behaviors, which are not evident in the description provided. Social communication disorder primarily involves difficulties in using language in social contexts rather than fluency issues. Hence, considering the signs Jeffery exhibits, cluttering is the most appropriate diagnosis.