Question

2.5.2 test (cst): computer - scored unit test
elements 1 and 3 are used to make the most common substance in the body.
what are these elements?
a. oxygen and sulfur
b. oxygen and hydrogen
c. hydrogen and helium
d. nitrogen and phosphorus

Explanation:

The most common substance in the body is water ($H_2O$), which is composed of hydrogen and oxygen.

Answer:

B. Oxygen and hydrogen