It's a salt of carbonic acid. it's called sodium bicarbonate. It contains the anion HCO3. It usually refers to bicarbonate of soda (baking soda), a white powder that is a common ingredient in antacids. It is also a byproduct of your body's metabolism.
Correct answer is D. shouted. To clamour means to express something loudly, and is usually associated with a loud outcry. The writer mentions word yells (to yell) in this sentence, which is also a synonym for shouting.