Which of these elements is essential to making up all organic molecules?

a. oxygen
b. hydrogen
c. carbon
d. nitrogen

The correct answer is (c) Carbon.

Organic compounds are the substance that contains carbon. The main property of carbon is catenation that make it prone to combine with the other carbon atoms. It is due to this property of carbon that a large number of organic compounds exists. The organic molecules have a very small amount of share on the surface of earth ,they are of prime importance because all the life processes are based on organic molecule. Some common examples are: Methane, Propane, Butane.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).