Which Event Represents the Process of Releasing Chemical Mediators

Which event represents the process of releasing chemical mediators?

A)
Histamine acting on smooth muscle
B) Binding of IgE by the Fc region to mast cells and basophils
C)
Prostaglandins causing vasodilation and increased vascular permeability
D) Binding of allergen to adjacent IgE binding sites on mast cells and basophils
E) Degranulation