The answer is "his face was as red as an apple".
Figurative language is the one that uses figures of speech to express ideas, but not literally. For example, the boy is ready to go out and his mother says: "you better take an umbrella; it's raining cats and dogs out there". She is not meaning animals falling from the sky.
In this case, the speaker resorts to a SIMILE, which is an implicit comparison between two different things, actions, or feelings by using AS or LIKE (e.g. my mind is like an open window).
