It would be in passive voice. For active voice, it would be something along the lines of, "The FBI opened the email."
"of insects" is an adjective phrase because it's a prepositional phrase that acts as an adjective. It modifies the word "group"; In other words, "of insects" is used to describe the word "group".
Answer:
The correct answer is A.
Explanation:
Whispering is something done by humans.
