Correct Answer: D

Rationale: The correct answer is D, ADH and aldosterone. Both antidiuretic hormone (ADH) and aldosterone increase water retention by the kidneys, thereby increasing blood volume. ADH acts on the kidneys to increase water reabsorption, while aldosterone acts on the kidneys to promote sodium reabsorption, leading to water retention. Choice A, ADH, is partially correct as it alone increases water retention. Choice B, aldosterone, is also partially correct as it alone increases water retention. Choice C, ANH (atrial natriuretic hormone), actually decreases water retention by promoting sodium excretion and inhibiting aldosterone release.

Correct Answer: C

Rationale: The correct answer is C: increased aldosterone secretion. Aldosterone, a hormone produced by the adrenal glands, increases sodium reabsorption in the kidneys, leading to retention of sodium and water in the interstitial fluid. Increased aldosterone secretion enhances the reabsorption of sodium, thereby increasing its retention. Choice A is incorrect because decreased aldosterone secretion would lead to less sodium reabsorption and increased excretion. Choice B is incorrect because increased ADH secretion primarily affects water reabsorption rather than sodium. Choice D is incorrect because decreased ADH secretion would lead to increased water excretion but not necessarily affect sodium retention.

Correct Answer: A

Rationale: The correct answer is the kidneys. The kidneys are primarily responsible for regulating fluid balance by filtering blood and adjusting the volume and concentration of urine. The lungs primarily regulate gas exchange, not fluid balance. The skin plays a role in temperature regulation and protection but is not the primary organ for fluid output. The intestines are mainly involved in the absorption of nutrients and water, rather than fluid output.

Correct Answer: D

Rationale: The correct answer is 'Electrolyte.' Electrolytes are substances that dissociate into ions when dissolved in water. Intracellular fluid, interstitial fluid, and plasma are not substances that dissociate into ions in a water solution. Intracellular fluid is the fluid inside cells, interstitial fluid is the fluid between cells, and plasma is the liquid component of blood. These choices do not dissociate into ions in a water solution, unlike electrolytes.

Correct Answer: B

Rationale: Chloride (Cl-) is the most abundant anion in blood plasma. It plays a crucial role in maintaining osmotic balance and acid-base homeostasis. Bicarbonate (Choice A) is important for buffering acids in the body but is not the most abundant negative ion in blood plasma. Hydroxide (Choice C) is not typically found in high concentrations in blood plasma. Phosphate (Choice D) is an important anion in the body but is not as abundant as chloride in blood plasma.