Which phoneme manipulation requires a child to replace one sound in a word with another?

Phoneme substitution is the correct answer because it involves a child changing one sound in a word to create a new word. For example, if you ask a child to change the /h/ in "hat" to /k/, they must replace it with another sound to say "cat." This manipulation helps children develop their understanding of how changing individual sounds, or phonemes, impacts words.

Phoneme addition refers to adding a sound to an existing word, which does not align with the requirement of replacing a sound. Phoneme blending involves combining separate sounds to form a word, rather than substituting one sound for another. Phoneme categorization requires identifying which sound is different in a set of words, not replacing sounds within a single word. Thus, phoneme substitution specifically captures the task of altering one sound in a word, making it the correct choice.