C is the awnser i hope this helped >_<
Answer:
amino acids
Explanation:
Proteins are made up of small units called amino acids. The proteins are composed of carbon, hydrogen, oxygen and nitrogen. In addition to nitrogen, proteins may contain phosphorus or sulphur or both. The proteins are referred to as nitrogenous compounds because they contain nitrogen element.
B. because the rock is formed and it goes younger as it grows the rock is still old on the inner layers but it adds new layers as it goes