While looking at a sample of blood in a microscope, you see a cell that is markedly larger than a red blood cell.

It has a bi-lobed nucleus and is filled with red granules in the cytoplasm.

What type of blood cell is this?

The correct answer is choice B. True.

As a result of the allergen-antibody reaction, mast cells release histamine.

This is because when mast cells are exposed to an allergen that binds to IgE antibodies attached to their FcɛRI receptors, they release histamine and other inflammatory mediators.

Histamine causes vasodilation, increased capillary permeability, mucus secretion, and smooth muscle contraction, which result in allergic symptoms such as itching, swelling, sneezing, and wheezing.

Choice A is wrong because it is the opposite of the correct answer.

Mast cells do release histamine in response to allergen-antibody reactions. Some additional sentences are:

Normal ranges of histamine levels vary depending on the tissue and the method of measurement, but they are usually low in healthy individuals and elevated in allergic conditions.

Histamine can be degraded by enzymes such as diamine oxidase and histamine N-methyltransferase, or inhibited by drugs such as antihistamines.

The lymph nodes of the axillary region receive lymph mainly from the upper limb and mammary gland.
This is because the axillary lymph nodes are located in the armpit area and drain the lymph vessels from the lateral quadrants of the breast and the arm.

Choice B is wrong because the abdominal viscera are drained by the celiac, superior mesenteric, and inferior mesenteric lymph nodes.
Choice C is wrong because the scalp and face are drained by the cervical lymph nodes.
Choice D is wrong because the thoracic viscera are drained by the bronchopulmonary, tracheobronchial, parasternal, and posterior mediastinal lymph nodes.