Question

Which two elements make up the most

common compound in the human body?

A. C and H
B. N and O
C. H and O
D. P and Ca​

Answer 1

C. H and O

Step-by-step explanation:

Almost 99% of the human body's mass is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus, in that order.

Element Symbol % in body

Oxygen O 65.0

Coal C 18.5

The human body is composed of 60% water, that is, H2O.