Hello there!
The answer to your question is:
A: Cite.
Example: When Timothy finished his research paper for his class, he made sure he added a page where it he had, "cited," all of the resources, to let the teacher know where he had found his facts and answers.
Definition: Cite; a verb- This word is used when quoting, or providing where the justification of an argument and/or subject matter originally came from.
I hope this helps! Have a wonderful day :)