Which of the Following Statements Is True Concerning Chronic Fluoride

Which of the following statements is true concerning chronic fluoride toxicity?

A) Drinking water with more than 2 ppm of fluoride can lead to fluorosis of tooth enamel during the age of tooth mineralization.
B) Dentinal hypoplasia is the most common sign of chronic fluoride toxicity during tooth development.
C) Color changes in tooth enamel caused by chronic fluoride toxicity are a result of hypermineralization of the outer one third of tooth enamel.
D) Children that drink water with at least 0.6 ppm of fluoride and ingest fluoride supplements are at risk for developing chronic toxicity.