Correct Answer: B

Rationale: Muscle weakness is a common sign of vitamin D deficiency. Vitamin D is essential for calcium absorption and bone health, and its deficiency can lead to muscle weakness. Brittle nails (Choice A) are not typically associated with vitamin D deficiency. Night blindness (Choice C) is related to vitamin A deficiency, not vitamin D deficiency. Hair loss (Choice D) can be linked to various factors, but it is not a common sign of vitamin D deficiency.

Correct Answer: B

Rationale: The correct answer is B: '21%'. Approximately 21% of persons in the United States who have HIV infection are unaware that they are infected. This percentage represents a significant portion of individuals who are not aware of their HIV status, highlighting the importance of increased testing and awareness campaigns. Choices A, C, and D are incorrect as they do not align with the estimated percentage provided in the context.

Correct Answer: B

Rationale: The best dietary advice for a patient with iron-deficiency anemia is to increase vitamin C intake. Vitamin C enhances the absorption of non-heme iron, which can help improve iron-deficiency anemia. Choices A, C, and D are not the best options for this condition. Increasing dairy consumption (Choice A) may not directly address the iron deficiency. Reducing red meat consumption (Choice C) may limit heme iron intake, which is easily absorbed by the body. Increasing fiber intake (Choice D) is generally beneficial but is not specifically recommended as the top advice for iron-deficiency anemia.

Correct Answer: D

Rationale: Nuts and seeds pose a choking hazard for children under 4 years old, making them an unsafe snack choice for young children. While low-fat milk or yogurt, whole-grain cereals, and raw vegetable sticks are healthy snack options suitable for children under 4 years old, nuts and seeds should be avoided due to the risk of choking, especially in young children who may not have fully developed chewing abilities.

Correct Answer: D

Rationale: Leg cramps are a common complication during hemodialysis due to shifts in fluid and electrolyte levels that occur during the treatment. Confusion (choice A) is not a common complication specifically related to hemodialysis. Profuse sweating (choice B) is not typically associated with hemodialysis complications. Hypertension (choice C) might be a pre-existing condition in some patients but is not a direct common complication of hemodialysis.