It's C. "Tiny, weightless crystals", doesn't have proper sentence structure at all, and sounds like there should've been more words with it.
The answer is flashback.
Flashback is a literary device in which the author describes circumstances which have happened before the present time in the course of the narration. It is used to provide background information so that the reader can have a deeper understanding of previous events and characters.
Answer:
...proper credits to the authors of the words or ideas that you incorporated into your paper. It allows those who are reading your work to locate your sources, in order to learn more about the ideas that you include in your paper.
Explanation:
Electronic: Email, Instant Messaging (e.g Gmail/Facebook)
Physical: Mail, Signs/Symbols (e.g Letters/Road Signs)
Unique: Braille