Which of the following is the process of meiosis for egg cell formation?

A. Cricoid cartilage: The cricoid cartilage is a ring-shaped structure located below the thyroid cartilage in the larynx. It provides support and maintains the airway but is not part of the glottis.

B. True vocal cords: The true vocal cords, or vocal folds, are part of the glottis. The glottis is the space between the vocal cords, and the vocal cords themselves are essential for sound production and phonation.

C. Thyroid cartilage: The thyroid cartilage is a large, shield-shaped cartilage in the larynx that forms the front of the laryngeal structure. It is not part of the glottis, though it surrounds the area where the vocal cords are located.

D. "Adam's apple": The "Adam's apple" is a colloquial term for the prominent part of the thyroid cartilage that is visible on the neck. It is not a structure within the glottis but rather an external feature of the larynx.

A. Androsterone and estradiol: Androsterone and estradiol are both sex hormones, but they do not function as antagonists. Androsterone is an androgen, and estradiol is an estrogen; they have different roles in sexual development and reproductive health but do not directly oppose each other.

B. Ghrelin and gastrin: Ghrelin and gastrin are hormones involved in regulating appetite and digestion. Ghrelin stimulates hunger, while gastrin stimulates gastric acid secretion. They do not act as direct antagonists to each other.

C. Insulin and glucagon: Insulin and glucagon are hormone antagonists that regulate blood glucose levels. Insulin lowers blood glucose by facilitating its uptake into cells, while glucagon increases blood glucose by promoting glycogen breakdown in the liver. Their actions counterbalance each other to maintain glucose homeostasis.

D. Calcitonin and melatonin: Calcitonin and melatonin have distinct functions; calcitonin helps regulate calcium levels in the blood, while melatonin regulates sleep-wake cycles. They do not have antagonistic effects on each other.