Answer: I think they should
Explanation:
A direct quote should NEVER be long-winded and lengthy. You want to try to get the point across in a carefully selected short excerpt, not copy a large portion of someone else's work and insert it into your paper with a little bit of your own writing.
The answer would be D. "I made just one request for the camping trip: I wanted to stay in a cabin instead of a tent."
Generally colons are used after phrases that are complete sentences. "I made just one request for the camping trip" is a complete sentence, and should therefore have a colon after it.