Concept:The smallest unit of meaning in speech is the morpheme, which cannot be broken into smaller meaningful parts.Explanation:- A morpheme is the smallest linguistic unit that carries a distinct meaning. For example, in the word "unable," the prefix "un-" is a morpheme meaning "not."- Other options do not represent the smallest unit of meaning: a syllable is a unit of sound, a phoneme is the smallest sound unit, and words are larger meaningful units composed of morphemes.- Therefore, among the given choices, only morpheme qualifies as the smallest unit of meaning in speech.Answer:Option A: morpheme