A12-year-old student who says "i-i-i-i want i-i-i-ice c-c-c-cream" is exhibiting

Fluency disorder
Fluency disorder is a communication disorder that involves discontinuous flow and timing of speech. It is mostly seen in children who are learning to speak. Physical tension, negative reactions, and avoiding of speaking situations work together with this disorder. Individuals with this disorder display repetition of words, sound extensions and long pauses when speaking. For the question given above, a 12-year-old student who says "i-i-i-i want i-i-i-ice c-c-c-cream" is exhibiting fluency disorder.

They create genetic variations