Answer:
The correct option is C.
Explanation:
Hypersensitivity is the process by which the immune system produce excessive reactions when exposed to certain antigens. There are four types of hypersensitivity, type 1 to type IV.
For hypersensitivity to occur some conditions must be fulfilled. For instance, an antigen must be present, the immune system must have been exposed to the antigen previously, etc. Hypersensitivity does not occur when the immune system is been exposed to an antigen for the first time.
