The clause "i wandered lonely as a cloud" is an example of a
a) alliteration.
b) hyperbole.
c) metaphor.
d) simile.

Your answer would be D) Simile.
This is because the clause compares the loneliness to a cloud, and similes are used to compare things, like "The food was as hot as the sun" or "The school was like a zoo".

I hope this helps!