Answer:
Example #2: A parenthetical citation.
Step-by-step explanation:
A.) If it were a part of the sentence, it would be much more embedded. For example, "...appears to be twice the of the preceding 80, according to 'Sea Levels Rise'".
B.) Also known as an MLA format citation. MLA citations are much more detailed than the given one because they need to include the author's name, the page in which it was cited, and must be completed with a complete reference in the works cited page.
This leaves you with only option C.