Reaction time is the answer
Maintaining personal hygiene is important to avoid the risk of contracting illnesses and infections.
I would say, A. Endoscopy because, it is a tube that goes down the throat or the other way and looks through the digestive tract and the throat cavity.
Because your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones ect. Protein is also an important building block of bones