Correct Answer: D

Rationale: The correct answer is phosphorus. Retention of phosphorus in patients with Chronic Kidney Disease (CKD) contributes to the development of bone disorders, including osteodystrophy, because it disrupts the balance of calcium and phosphorus in the body. This imbalance leads to a variety of bone diseases. The other options - iron, sodium, and potassium - while important in the overall metabolic function, are not directly linked to the development of bone diseases in CKD patients due to retention.

Correct Answer: B

Rationale: This scenario illustrates depression or social isolation as a risk factor for malnutrition. After the death of his wife, the elderly man may have experienced depression or social isolation, which can lead to decreased food intake and poor nutritional status. Although age, chronic illness, and impaired mobility can also contribute to malnutrition, they are not the primary factors described in this scenario. The history of chronic illness (Choice A) and impaired mobility (Choice D) were not mentioned in the scenario, and while age (Choice C) is a factor, it's not the main factor depicted in this case.

Correct Answer: D

Rationale: Carbohydrates, fats, and proteins are the three macronutrients that provide energy (calories) to the body. Carbohydrates are the body's primary source of energy, fats act as a secondary source when carbohydrate energy is exhausted, and proteins are used for energy when carbohydrate and fat sources are low. Choice D, Water, is essential for the body's functions, but it does not provide energy.

Correct Answer: D

Rationale: Smoking is a major risk factor for atherosclerosis. It significantly contributes to the buildup of plaque in the arteries and thereby increases the risk of cardiovascular diseases. On the other hand, exercise is generally beneficial for cardiovascular health and is not a risk factor for atherosclerosis. Excessive sun exposure and insufficient vaccinations have no established links to atherosclerosis, making them incorrect options for this question.

Correct Answer: D

Rationale: Bile, which is produced by the liver and stored in the gallbladder, aids in the digestion of fats. It does this by emulsifying the fats, which makes them easier for the digestive enzymes, such as lipase, to break down. While choices A, B, and C could be seen as partially correct since fats are a type of lipid and the process of breaking down fats could be seen as breaking down lipids, the most accurate answer is D, as the primary function of bile is to aid in fat digestion, not the digestion of all types of lipids or the digestion of proteins or carbohydrates.