The term "vetted" means "to make a careful examination," or "to investigate someone thoroughly." It is commonly used to ensure someone is trustworthy for a job. When Whitehurst says that the candidates have already been "extremely vetted," it is implied that the candidates were investigated to a great extent.
"A" is the correct choice :)
Answer:
America is the only.country that uses the metric system
Details about what the police did
Answer:
new I'd just for emergency