What statement best describes the molecules found in living systems?
a. they contain mostly sulfur, gold, and lead.
b. they are very simple molecules made of carbon and hydrogen
c. they are very complex molecules made mostly of carbon, hydrogen, and oxygen

c

explanation:

molecules found in living systems are very complex molecules made mostly of carbon, hydrogen, and oxygen.

The compound is formed from definite proportions of atoms of different elements and they formed through the bonding. The compound formed takes on very different properties from the ones of their origin elements. Thus, the answer is the third choice.