Answer:
Metaphor
Step-by-step explanation:
The figurative language used in the sentence 'Mary is a packrat' is a metaphor. A metaphor is a figure of speech in which comparison is drawn between two things. The two things possess one quality similar to each other. All the other qualities are very different. Mary here is referred to as a 'packrat'. A packrat collects things which are not even usable. Hence, the qualities of collecting things which are not usable are similar between a rat and Mary. Hence it is an example of a metaphor.