Approximately 75% of reputable producers of bottled water use groundwater as their water source. Plain tap water is the most natural source of fluids.

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, Vitamin C. Vitamin C is a water-soluble vitamin, not fat-soluble. Fat-soluble vitamins are Vitamins A, D, E, and K. These vitamins are stored in the body's fat tissues and liver, unlike water-soluble vitamins which are not stored and are eliminated in urine, making them less likely to reach toxic levels.

Correct Answer: C

Rationale: Vitamin A can be stored in the liver to meet basic needs for at least 1 year. This storage capacity allows the body to have a reserve of Vitamin A to sustain its needs over an extended period. Choices A, B, and D are incorrect because they underestimate the storage capacity of Vitamin A in the liver, which can last longer than these durations.

Correct Answer: B

Rationale: Both statements are false. Studies suggest that leukoplakia, a white plaque that forms on oral mucous membranes, can be resolved by vitamin A, retinoids, and beta-carotene. Despite the potential to resolve leukoplakia, relapse is common. Also pertinent, evidence does not indicate that any of these nutrients prevent malignant transformation. The extract provided clarifies that leukoplakia is a white plaque, not an erythematous lesion, and that vitamin A, retinoids, and beta-carotene can help resolve it.

Correct Answer: A

Rationale: Both the statement and the reason are correct and related. Inadequate intake of vitamin A in lower socioeconomic groups is due to a lack of resources to purchase and consume vegetables and fruits. This is supported by the fact that the average intake in the United States meets the Recommended Dietary Allowance (RDA) for vitamin A intake, except in lower socioeconomic groups. These individuals often lack the financial means to buy, prepare, and eat a variety of fruits and vegetables, leading to deficiencies. It's important to note that because vitamin A can be stored in the liver, most adults have sufficient quantities to maintain health. Choices B, C, and D are incorrect because the statement and reason are both accurate and logically connected, as the lack of resources directly impacts the ability to obtain necessary sources of vitamin A.