Correct Option: D

The composition of the human body can be looked at from the point of view of either mass composition, or atomic composition. To illustrate both views, the human body is 70% water, and water is 11% hydrogen by mass but 67% hydrogen by atomic percent. Thus, most of the mass of the human body is oxygen, but most of the atoms in the human body are hydrogen atoms. Almost 99% of the mass of the human body is made up of the six elements oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All are necessary to life. The remaining elements are trace elements, of which more than a dozen are thought to be necessary for life, or play an active role in health (e.g., fluorine, which hardens dental enamel but seems to have no other function).