Which type of bond involves two nonmetals? covalent
ionic
metallic
polar

ANSWER A, COVALENT

Covalent bonds form when electrons are shared between two nonmetals — (A)

The correct answer among the choices given is third option. Without the carbon-oxygen cycle, most life would not exist. Most life here on Earth needs oxygen and carbon in order to survive without these gases life will come to an end. Most especially humans, animals and plants.