Respuesta :
Answer: Fluoride
Explanation:
Fluoride is helpful in preventing the decay of tooth. It has been added in the water supplies for the lasts 70 years to keep the tooth and body healthy.
Now it has added to toothpaste in order to strengthen the enamel, hard surface of the tooth and oral hygiene.
It is a type of mineral which is necessary for the good health of teeth.It is a natural cavity fighter.
hence, the correct answer is fluoride.