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