Respuesta :

Karima6
The answer is:
A. Oxygen

Air contains more than one substance, water is chemically made up of oxygen and hydrogen, and sodium chlorine is a mixture of sodium and chlorine.

Hope it helps :)
weatherbug02
The answer is A. Oxygen.

Oxygen is the only element of the answer choices. D. is considered a compound because it's made up of two elements from the periodic table. B. and C. are not considered elements in the periodic table either.

Therefore, the answer is A.