Which of the following is associated with the thymus?
a. b cells
b. t cell maturation
c. natural killer cells
d. complement

Option B. "T Cell maturation"

Explanation:

T-cell, also known as T lymphocyte, are primary type of leukocyte or white blood cell important part of the immune system.

Bone marrow is the origin of T-cells and then get mature in the thymus. In thymus, T- cells differentiate or multiply into regulatory, or cytotoxic T-cells helper, or act as memory T-cells.

T-cells then  move in lymphatic system, once get stimulated by appropriate antigen, helper T-cells secrete cytokines that stimulate antibody-producing cells called B cells. Regulatory T-cells control immune reactions while Cytotoxic T-cells kill infected cells or cancer cells.

Hence, the correct answer is Option B.

the ileocecal valve (also called bauhin valve), which limits the rate of food passage into the cecum and may prevent material from returning to the small intestine.

auricle

explanation:

the flaps on the front of the atria are called the auricle.