They are referring to when Dr. Rank performed medical tests to see if he was dying or not.
I'll have to go with D, but ask yourself:
"Which environment best matches the scene?"
Choices 1, 2, and 4 are correct.
Answer:
"First, the plesiosaur is an air breather." is the line from the article that best disproves the plesiosaur theory. In the article, the author argues that because plesiosaurs were air breathers, they would need to come up for air more frequently than any sightings ever occur. As there are so few "sightings" every year and supposedly fewer now than ever, it is unlikely that Nessie is a plesiosaur.
Explanation: