Answer:
B. Metaphor.
Explanation:
Metaphors are the literary devices used by writers in comparing one thing to another but which cannot be literally done or made in reality. This figure of speech enables to make the sentences more colorful and more attractive. It is also used to provide clarity or expanse the meaning of the things being described, thereby allowing the readers to better understand the work.
Here, the comparison of the sky as a painting canvas give a dramatic representation of the beauty of the sky, though it being a canvas and waiting to be painted by the stars is impossible or literally impossible. This metaphorical representation of the sky as a painting canvas gives more character to it than being simply described in simple words.
