It’s C. Plural. When using a word that contains an s, for example “ducks” it is more than one.
Really it depends upon what the author makes it. If it's a published book, it's a for entertaining purposes. If it was informal, it's be a biography.
Answer:
The answer are the words "stalk and defenseless."
Explanation:
The words that make it obvious how the author feels about the birds are stalk and defenseless because the author is describing how the fish in the lake fall victim to the birds. It seems the author does not like the birds for their instinct to stalk their prey by watching the fish in the lake closely. The author seems dismayed that it would only take the ospreys a moment to catch the fish who have no way to defend themselves against the birds.
The answer is the last one, D. All of the other transitions indicate that the writer will either go into further detail on the subject or list other reasons as to why this would be correct. However, D clearly uses a contrasting transition to introduce a new argument.