Answer:
D. metaphor
Step-by-step explanation:
A metaphor is a figure of speech that directly asserts that one element is similar or equal to another element. This figure of speech is use comparisons to describe an event, someone, a place, etc., without using the words "like" "as", "such as" like similes do. Therefore, "Antony is but a limb of Caesar" is a metaphor because the statement figuratively asserts that Antony is something else.