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

As good as gold

Simile

The figure of speech used in the expression "As good as gold" is simile.

A simile is a figure of speech in which two things are compared using the words "like" or "as." In this case, the person's character is being compared to the value and purity of gold. This creates a sense of the person's goodness and trustworthiness.

The other answer choices are incorrect. Metaphor is a comparison between two things without using the words "like" or "as." Personification is a figure of speech in which inanimate objects are given human qualities. Alliteration is the repetition of consonant sounds at the beginning of words. None of these devices are used in the expression "As good as gold.".