Which of the following statements about the depletion of ozone layer is correct?

The problem of ozone depletion is less serious at poles because NO$$_2$$ solidifies and is not available for consuming ClO• radicals.

The problem of ozone depletion is more serious at poles because ice crystals in the clouds over poles act as catalyst for photochemical reactions involving the decomposition of ozone of Cl• and ClO• radicals.

Freons, chlorofluorocarbons, are inert. Chemically, they do not react with ozone in stratosphere.

Oxides of nitrogen also do not react with ozone in stratosphere.