Answer:
allusion
Explanation:
In literature, an allusion is an "unexplained reference to something or someone outside of the text". The reference is usually to someone or something popular, like Mark Twain.
Question 17 answer is D none of the above
Question 18 answer is A a recording of events
Question 19 answer is A a laboratory for stars
Question 20 answer is B a room which gets a lot of sunlight
b because it is the only one that makes sense