Correct Answer: B

Rationale: Iron deficiency is the most common nutrient deficiency globally. It leads to anemia and affects many populations, especially women and children. Magnesium, selenium, and zinc deficiencies are important, but they are not as prevalent as iron deficiency on a global scale.

Correct Answer: A

Rationale: The correct answer is A: Iron. Iron is an essential nutrient needed by the body to make hemoglobin, the protein in red blood cells that carries oxygen. While other nutrients like vitamin B12, niacin, and folate are important for various bodily functions, they are not directly involved in the production of hemoglobin. Vitamin B12 is essential for nerve function and DNA synthesis, niacin is important for metabolism, and folate is crucial for cell division and DNA synthesis. Therefore, only iron is specifically required for hemoglobin production.

Correct Answer: B

Rationale: Iron deficiency is the most common nutrient deficiency globally. It leads to anemia and affects many populations, especially women and children. Magnesium, selenium, and zinc deficiencies are important, but they are not as prevalent as iron deficiency on a global scale.

Correct Answer: A

Rationale: Plant stanols and sterols are commonly added to margarine to help lower LDL cholesterol levels. Margarine acts as a vehicle for these compounds, making it easier for individuals to incorporate them into their daily diet. While milk, cereal, and yogurt are healthy food options, they are not typically enriched with plant stanols and sterols for cholesterol-lowering purposes, making them less likely candidates as the correct answer.

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.