What is the most likely meaning of the simile in the following sentence?

The birds started singing at 5 a.m., sounding like a company of fire engines headed to a huge blaze.

A. It suggests that the speaker believes fire engines are too loud.
B. It suggests that the birds were communicating an urgent message to one another.
C. It suggests that the speaker was woken up by the birds.
D. It suggests that the birds were loud and unpleasant sounding.