Answer: B. Metaphor.
Explanation: a metaphor is a figure of speech that consists in making a direct comparison between elements that aren't obviously related, in order to create an image in the reader's mind. In the given sentence, we can see a clear example of a metaphor that compares the night sky with a blank canvas. The other options don't make sense because a hyperbole is an exaggeration, a simile is a comparison but using the words "like" or "as" and an allusion is a reference.