Ozone is created when energetic photons from the sun such as the UV strikes a molecule of oxygen splitting the two atoms. The radical atom then bombards with another oxygen molecule and join to create an O3 complex called ozone. The rate at which the ozone is created is balanced by the rate at which it is destroyed by the same energetic photons.
Option a, b and c are examples of not practicing proper hygiene and they increase the chances of you getting diseases. Option D is the only example that practices proper hygiene.