Read the excerpt below from "Blow, Blow Thou Winter Wind" and answer the question that follows.

Blow, blow, thou winter wind
Thou art not so unkind
As man's ingratitude;
Thy tooth is not so keen,
Because thou art not seen,
Although thy breath be rude.

In the poem, the comparison of the wind to man's character is _______ .
a. a motif
b. an inference
c. an extended metaphor
d. an allusion