What speech disorder affects the ability to form coherent words?

The correct choice focuses on apraxia, a motor speech disorder characterized by difficulty in planning and coordinating the movements needed for speech. Individuals with apraxia know what they want to say but struggle to form the words correctly, often leading to inconsistent speech production. This disorder can result in sounds being omitted, added, or distorted, making speech difficult to understand. It affects the ability to execute the precise movements involved in speech, rather than the understanding or production of language itself.

Other options, while related to speech and communication, pertain to different aspects of speech disorders. Dysarthria involves weakness or paralysis of the muscles used for speaking, affecting the clarity and intelligibility of speech, rather than the ability to form words themselves. Aphasia specifically impacts language comprehension and expression, affecting a person's ability to find words or produce sentences, which is distinct from the coordination issues seen in apraxia. An articulation disorder pertains to difficulties pronouncing specific sounds and often involves distortion or substitution, but again, this does not encompass the broader planning difficulties found in apraxia.