Which of the following words contains multiple phonemes?

The choice "Sun" contains multiple phonemes, making it the correct answer. Phonemes are the distinct units of sound in a specified language that distinguish one word from another. In the case of "Sun," it can be broken down into three individual phonemes: /s/, /ʌ/, and /n/. Each of these contributes to the overall pronunciation of the word.

In contrast, the other words contain fewer phonemes. For instance, "Book" consists of three phonemes: /b/, /ʊ/, and /k/. Thus, while still containing multiple phonemes, the emphasis of the question may likely be in distinguishing the number and the variety of phonemes present across the choices. In other words, the phonetic breakdown of "Sun" clearly demonstrates its diverse phonemic structure.