Concept:Plaque is a sticky film of bacteria, food remains and saliva that builds up on the teeth, especially at the gum line and in the corners between teeth.
Explanation:If plaque is not removed by brushing and flossing, minerals from saliva harden it into a hard yellow, brown or greenish-black deposit (hardened plaque, also called tartar or calculus).
Caries and cavities are the holes and decay that plaque bacteria cause; gum disease is the inflamed gums it causes. They are effects, not the deposit itself.
Key point: The deposit is plaque (in its hardened form, tartar). Caries, cavity and gum disease are what plaque leads to.
Answer:Option B (plaque)