Oxygen molecule has two unpaired electrons. It is therefore,

Explanation

A ferromagnetic substance, like iron, retains magnetic properties after removing the field. On the contrary, oxygen does not have this magnetic property once the field is removed; hence, it is a paramagnetic substance. B: Diamagnetic substance: The compounds or molecules which have only the paired electron in their orbital are called diamagnetic substances. C: Electromagnetic is used to describe the electrical and magnetic forces or effects produced by an electric current. D: Paramagnetic substance: The compounds or molecules which have at least an unpaired electron in their orbitals are called paramagnetic substances. In an oxygen molecule, there are two unpaired electrons in its molecular orbital. So it has paramagnetic properties. As free electrons move on their axis to produce a magnetic field. Hence, oxygen is a paramagnetic substance.