Which of the following describes hallmark features of stuttering?

The hallmark features of stuttering include repetitions, prolongations, and blocks. Repetitions involve the involuntary repetition of sounds, syllables, or words (e.g., "I-I-I want to go"). Prolongations refer to extending sounds (e.g., "ssssssmile"), where a person can elongate a sound beyond typical speech patterns. Blocks are moments when the person is unable to produce sounds despite wanting to speak, often characterized by tension or struggle. These features are central to the nature of stuttering and distinguish it from other speech-related challenges.

The other options, while related to speech and language, do not accurately characterize stuttering. Fast speech and clarity, for example, do not align with the disruptions seen in stuttering. Inability to speak could suggest severe anxiety or other conditions but does not specifically define stuttering. Articulation errors focus on the production of individual speech sounds and are not defining characteristics of stuttering itself.