The antibodies produced in allergic reactions:

Calcitonin is a hormone that protects against excessive blood calcium levels by inhibiting bone turnover and decreasing reabsorption.
It is produced by the thyroid gland and acts on both osteoclasts and osteoblasts.
Choice B is wrong because parathyroid hormone (PTH) stimulates both resorption and formation of bone, and controls the level of calcium in the blood.
Choice C is wrong because thyroxine is a thyroid hormone that is required for skeletal maturation and influences adult bone maintenance but does not directly affect calcium deposition into bone.
Choice D is wrong because insulin is a hormone that regulates both bone formation and bone resorption but does not specifically stimulate calcium deposition into bone.

Persons with type AB blood are sometimes called universal recipients, not donors. This means they can safely receive a blood transfusion using any other blood type. Choice A is wrong because it confuses type AB blood with type O negative blood.

Type O negative blood is considered the universal donor type because it has no antigens on the surface of red blood cells and can be given to people of any blood type.

Type AB-positive blood is also considered the universal plasma donor type because it has both A and B antigens and can be given to patients with any blood type.

Plasma is the liquid part of blood that carries cells and proteins throughout the body.

The presence or absence of antigens and the Rh factor determine how a person’s immune system reacts to a blood transfusion or organ transplant.

Antigens are substances that can trigger an immune response if they are foreign to the body.

The Rh factor is a protein that can be either present (+) or absent (-) on the surface of red blood cells.