Which of the Following Statements About Using Antihistamines in the Treatment

Which of the following statements about using antihistamines in the treatment of anaphylaxis is TRUE?

A) Antihistamines displace histamine, then block histamine receptors.
B) Antihistamines block histamine receptors and reduce histamine release from mast cells and basophils.
C) Blocking of H1 receptors results in mild vasoconstriction, while the blocking of H2 receptors results in bronchodilation.
D) Antihistamines block H1 and H2 receptors and prevent further release of histamine from B and T cells.