The correct option is A Intine is a thick, non-continuous inner layer of pollen grain.
Intine is the inner layer of pollen grain, however it is thin and a continuous layer made up of cellulose and pectin.
Exine is the outer hard layer of pollen wall. It is made up of sporopollenin.
Most species of pollen grains can cause allergic reactions.
Pollen grains can be stored in liquid nitrogen (-196 degrees Celsius) for many years.