The two forms of oxygen found in the atmosphere are
(a) water and ozone
(b) water and oxygen
(c) ozone and oxygen
(d) water and carbon-dioxide
Oxygen does not exist in atomic form. Pure oxygen atoms are found in molecular form. A molecular form in which two oxygen atoms come together is called oxygen gas. A molecular form in which three oxygen atoms come together is called ozone.
Hence the correct option is C.