Assertion : Mast cells in the human body release excessive amounts of inflammatory chemicals which cause allergic reactions.
Reason : Allergens in the environment on reaching human body stimulate mast cells in certain individuals.

If both Assertion and Reason are true and the reason is the correct explanation of the assertion

If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

If Assertion is true statement but Reason is false

If both Assertion and Reason are false statements

Solution

If both Assertion and Reason are true and the reason is the correct explanation of the assertion

Mast cells act on body's defense mechanism. When some allergens like different pollutants, smog, smoke, pollen grains etc. come in contact with mastcell, they stimulate the mast cells. The allergic reaction is triggered by cross linking of IgE molecules on the surface of mast cells by allergen. And ultimately mast cells release excessive amounts of inflammatory chemicals which cause allergic reactions.