Correct Answer: A

Rationale: Both statements are true. Approximately 75% of reputable producers of bottled water use groundwater as their water source, which is the same source as the public water supply. Plain tap water, coming from underground sources or reservoirs, is indeed a natural source of fluids. The first statement is supported by the fact that groundwater is a common source for bottled water due to its purity and taste. The second statement is true as tap water is sourced from natural reservoirs or underground aquifers in most cases, making it a natural fluid source for consumption. Other choices are incorrect because both statements are factually accurate based on common practices in the production and sourcing of bottled water and tap water.

Correct Answer: B

Rationale: The correct answer is B. Magnesium plays an important role in maintaining calcium homeostasis and preventing skeletal abnormalities. It is involved in more than 300 enzymatic reactions, including energy metabolism, insulin activity, and glucose use. Magnesium is vital to the structural integrity of heart muscle and other muscles and nerves. While magnesium does play a role in blood clotting, nerve impulses, muscle contraction, relaxation, ATP energy release, and metabolism of fats, carbohydrates, proteins, the primary physiologic role of magnesium in the body is related to calcium homeostasis and maintaining the structural integrity of the heart muscle. Choice A is incorrect because it includes functions of magnesium, but they are not its primary physiologic role. Choice C is incorrect as magnesium has several known metabolic functions. Choice D is incorrect because although magnesium is involved in ATP energy release and metabolism, its primary role is related to calcium homeostasis and structural integrity of muscle.

Correct Answer: B

Rationale: Rickets is caused by vitamin D deficiency, not vitamin C deficiency. It usually occurs in children who are 1 to 3 years old. The name rickets came from the word 'wrikken,' meaning 'to bend or twist.' Common manifestations of rickets include tachetic deformities like bow legs or knock-knees, a narrow and distorted chest, and failure of the epiphyses of bones to develop normally, resulting in twisted and warped bones. While the diagnosis of rickets may be increasing in the United States, it is not caused by a lack of vitamin C.

Correct Answer: A

Rationale: The correct answer is A, Type 1 Diabetes. The prevalence of Type 1 Diabetes is seen in approximately 5% to 10% of cases. This statement highlights a key epidemiological characteristic of Type 1 Diabetes. Choice B, Type 2 Diabetes, is incorrect because the prevalence mentioned does not align with Type 2 Diabetes, which has a much higher prevalence in the general population. Choices C and D are not relevant to the question and can be disregarded.

Correct Answer: C

Rationale: The correct answer is Vitamin D. Although vitamin D, also known as calciferol, has been called a vitamin, it is more appropriately classified as a hormone. Like hormones, vitamin D acts to control the function of other cell types. For example, it helps the body absorb and regulate skeletal calcium and phosphorus levels. Choice A (Vitamin A) plays a crucial role in vision and immune function. Choice B (Vitamin B) is a complex of different vitamins that play various roles in the body. Choice D (Vitamin C) is important for collagen production and acts as an antioxidant.