Question

What is one of the main reasons writers like thoreau use metaphor in their writing?

a. to give objects human qualities
b. to reinforce key ideas
c. to make rhyming easier
d. to create strong rhythms

Answer 1

b. to reinforce key ideas

Answer 2

Not A because that's personification: giving objects human qualities.

Understand the definition of metaphor.
According to Webster dictionary a metaphor is :
a figure of speech in which a term or phrase is applied to something to which it is not literally applicable in order to suggest a resemblance, as in “A mighty fortress is our God.”

I agree with answer being B.