Q. Which among the given is the hardest substance in the human body -

Explanation by: Official MCQ Buddy

Enamel is the hardest substance in the human body. It covers the outer layer of the teeth and is highly mineralized, consisting mainly of hydroxyapatite (calcium phosphate).
Bone (B) and Dentine (D) are also hard but not as strong as enamel.
Nail (C) is made of keratin, which is much softer compared to enamel.
Thus, tooth enamel is the hardest substance in the human body.