Which is the best definition of metaphor?

A.
a figure of speech that makes a comparison using the words like or as; for example, "I'm as hungry as a horse"

B.
a figure of speech that states a comparison between two unlike things; for example, “I’m the dew on the rose”

C.
a figure of speech that makes a comparison using numbers; for example, "I am one of two artists here today"

D.
a figure of speech that states a comparison between the speaker and another person; for example, "I am older than Sheila"