From the given options, select the Figure of Speech (Poetic Device) used in the expression:

By apt alliteration's artful aid

Alliteration

The correct answer is Alliteration.

The expression "By apt alliteration's artful aid" is an example of alliteration, which is the repetition of the same consonant sound at the beginning of closely connected words. In this case, the repeated consonant sound is the "a" sound. This is alliteration because the words "apt," "alliteration," and "artful" all start with the "a" sound.

The other options are incorrect. Personification is a figure of speech that gives human qualities to inanimate objects or animals. Oxymoron is a figure of speech that juxtaposes two contradictory terms. Simile is a figure of speech that compares two things using the words "like" or "as."