Which is the hardest substance in the human body?
ASkull
BKnee cap
CRib
DTooth enamel
Correct answer
D. Tooth enamel
Explanation
Enamel is the hardest substance in the human body and contains the highest percentage of minerals, 96%, with water and organic material composing the rest. The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate