Which example demonstrates an allophone?

The example of "k in keep versus k in kite" illustrates an allophone because it showcases two different phonetic realizations of the same phoneme /k/. In phonetics, allophones are variations of a phoneme that occur in specific phonetic contexts without changing the meaning of the word.

In this case, the /k/ sound in "keep" is produced with a slightly different articulation compared to the /k/ in "kite." The /k/ in "keep" is typically aspirated, meaning there is a burst of air that follows the consonant sound, while the /k/ in "kite" is unaspirated. Despite these differences in articulation, both sounds represent the same phoneme in English, which is /k/. Therefore, this example effectively illustrates the concept of allophones.

While the other options present contrasting sounds—like different phonemes or vowels—this pair shows variation in the realization of a single phoneme, fitting the definition of allophones perfectly.