Final answer:
The smallest unit of sound that can carry meaning is a morpheme, which may consist of one or multiple phonemes. Morphemes form the semantic content of words, while phonemes are the basic sound units.
Step-by-step explanation:
The smallest unit of sound that can carry meaning is B. Morphemes. A morpheme may consist of a single phoneme (like the English word 'a') or multiple phonemes (like the word 'swimming', which combines the morphemes 'swim' and the present participle '-ing'). Words are constructed by combining various phonemes, which are the basic units of sound in a language. However, it is the morphemes that carry the semantic weight. Semantics is concerned with the meaning derived from morphemes and words, while syntax addresses the organization of words into sentences. Speech sounds can be categorized as vowels, semi-vowels, or mutes based on the articulatory process. Furthermore, attributes of sound waves such as frequency and amplitude determine the perceptual characteristics like pitch and loudness.