Final answer:
The sentence 'Suzy saw seashells on the seashore' demonstrates alliteration due to the repeated 's' sound in close proximity. On the other hand, it does not use onomatopoeia, which imitates the source of sound.
Step-by-step explanation:
The sentence 'Suzy saw seashells on the seashore' is an example of alliteration. Alliteration is a literary device where the first consonant sounds in close proximity are repeated. In this case, the repeated 's' sound in 'Suzy', 'saw', 'seashells', 'seashore' gives it this stylistic feature. On the other hand, onomatopoeia is a term for words that phonetically imitate or suggest the source of the sound they are describing, e.g., 'buzz', 'boom', etc. This sentence does not use onomatopoeia.
Learn more about Alliteration and Onomatopoeia