Which literary device is most prominently used in the sentence, "Fiona waited, watched, and wondered aloud, 'When will the geese return, winging their way across the sky?'

The sentence illustrates alliteration through the repetition of the initial consonant sound in the words "waited," "watched," and "wondered." Alliteration is a literary device that enhances the rhythm and musical quality of a phrase, drawing attention to the words and adding a layer of texture to the writing. In this case, the repetition of the 'w' sound creates a pleasing auditory effect and emphasizes Fiona's state of anticipation and curiosity.

The other choices do not apply here. Personification would involve giving human traits to non-human entities, which is not present in this sentence. A metaphor is a direct comparison between unrelated things, and similes compare using "like" or "as," neither of which are used here. Thus, the prominent use of alliteration in the sentence correctly identifies this literary device.