Correct Answer: A

Rationale: Enlargement of the thyroid, known as a goiter, can compress the nearby structures in the neck, including the esophagus. This compression can lead to symptoms such as difficulty swallowing (dysphagia) or a sensation of pressure in the throat.
Therefore, an enlarged thyroid gland is expected to affect swallowing.

Choices B, C, and D are incorrect because a goiter primarily affects structures in the neck due to its physical enlargement, rather than directly impacting insulin levels, sleep, or digestion.

Correct Answer: A

Rationale: Potassium is the mineral that helps maintain fluid balance in the body. It plays a crucial role in regulating the amount of fluid inside and outside the body's cells, thereby helping to maintain proper hydration levels. Potassium works in conjunction with sodium to regulate fluid balance and is essential for proper muscle function, nerve transmission, and heart health. Cobalt, chromium, and sulfur do not play significant roles in maintaining fluid balance in the body, making them incorrect choices for this question.

Correct Answer: B

Rationale: The urinary system, specifically the kidneys, is primarily responsible for regulating electrolytes in the body by filtering and excreting excess electrolytes, such as sodium, potassium, and chloride, through urine. The kidneys play a crucial role in maintaining the body's electrolyte balance, which is essential for various bodily functions and overall health. The endocrine system regulates hormones, the lymphatic system is involved in immunity, and the nervous system controls communication in the body.
Therefore, the correct answer is B, the urinary system, as it directly handles electrolyte regulation by adjusting their excretion levels.

Correct Answer: D

Rationale: The correct answer is D: T4. The primary hormone secreted by the thyroid gland is thyroxine, also known as T4. T4 plays a crucial role in regulating metabolism, growth, and energy levels in the body. It is converted into the more active form, triiodothyronine (T3), which exerts most of the biological effects of thyroid hormones.

Choices A, B, and C are incorrect. Oxytocin is not produced by the thyroid gland but by the pituitary gland, TSH (thyroid-stimulating hormone) is secreted by the pituitary gland to stimulate the thyroid gland, and adrenaline is produced by the adrenal glands, not the thyroid gland.

Correct Answer: C

Rationale: The correct answer is 'C: anterior.' The term 'anterior' refers to a position in front of or toward the front of the body. In this case, the ribs are positioned in front of the lungs when considering the anatomical position. The term 'medial' means toward the midline of the body, 'superior' means above or higher in position, and 'deep' refers to a position farther from the surface or external part.
Therefore, the most appropriate choice is 'anterior' when describing the relationship between the ribs and the lungs.