Endocrine and Exocrine Glands

The endoderm gives rise to the epithelium of the pharynx, including the eustachian tube, the tonsils, the thyroid gland, parathyroid glands, and thymus gland; the larynx, trachea, and lungs; the gastrointestinal tract (except mouth and anus), the urinary bladder, the vagina (in females) and the urethra. The adrenal glands develop from two separate embryological tissues; the neural crest ectoderm and the intermediate mesoderm.

Our body had one pair of adrenal glands, one at the anterior part of each kidney. The gland is composed of two types of tissues. The centrally located tissue is called the adrenal medulla and outside this lies the adrenal cortex.

The endocrine gland present on the kidney is the Adrenal gland. The adrenal gland produces various type of hormones like adrenaline and the steroids aldosterone and the cortisol. Each gland has an outer cortex which produces steroid hormones and an inner medulla.

Symptoms of tetanus include
 a)Tetanus often begins with mild spasms in the jaw muscles known as lockjaw. The spasms can also affect the facial muscles and experience spasms and stiffness in various muscles, especially those in jaw, abdomen, chest, back, and neck.
b)Muscle cramps or spasms in your legs, fever, high blood pressure etc
Hypoparathyroidism is decreased function of the parathyroid glands with underproduction of parathyroid hormone. This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany (involuntary muscle contraction).
Hence parathyroid gland is associated with tetanus.
So, the correct answer is 'Parathyroid gland'.

The thymus is a specialized organ of the immune system. Within the thymus, T cells or T lymphocytes mature. At birth, it is about 5 cm in length, 4 cm in breadth, and about 6 mm in thickness. The organ enlarges during childhood and atrophies at puberty. The thymus is at its largest in children. The thymus reaches maximum weight (20 to 37 grams) by the time of puberty. As one ages, the thymus slowly shrinks, eventually degenerating into tiny islands of fatty tissue. By the age of 75 years, the thymus weighs only 6 grams.

Hassall's corpuscles (or thymic corpuscles) are structures found in the medulla of the human thymus, formed from eosinophilic type VI epithelial reticular cells arranged concentrically. 

Endoderm, the innermost of the three germ layers, or masses of cells (lying within ectoderm and mesoderm), which appears early in the development of an animal embryo. The endoderm subsequently gives rise to the epithelium (tissue that covers, or lines, a structure) of the pharynx, including the eustachian tube, the tonsils, the thyroid gland, parathyroid glands, and thymus gland; the larynx, trachea, and lungs; the gastrointestinal tract (except mouth and anus), the urinary bladder, the vagina (in females), and the urethra. 

Thymosins secreted by thymus  play a major role in the differentiation of T-lymphocytes, which provide cell-mediated immunity. In addition, thymosins also promote production of antibodies to provide humoral immunity.

Hassall's corpuscles also called thymic corpuscles, are structures found in the medulla of the human thymus, formed from eosinophilic type VI epithelial reticular cells, arranged concentrically.
Thus, the correct answer is option (A), 'Thymus'.

Thymus is small lymphoid structure present in lower art of neck in front of trachea, below the thyroid gland. It is the primary source of lymphocytes before birth and is the site of maturation or development of T-lymphocytes which circulates in lymphoid tissues. 

Thymus becomes inactive after puberty and shrinks. Most of the glands is replaced by adipose tissue. It produces thymosin which stimulates the development of disease-fighting T cells. The immune system produces most of its T cells during childhood and requires very few new T cells after puberty so the gland degenerates.