Correct Answer: A

Rationale: Carbohydrates are composed of carbon, hydrogen, and oxygen. These three elements combine to form the basic structure of carbohydrates. Oxygen is an essential element in carbohydrates, contributing to their chemical composition. Choice B (nitrogen) is incorrect as nitrogen is not a typical component of carbohydrates. Choice C (water) is incorrect as water is not an element but a compound composed of hydrogen and oxygen. Choice D (glucose) is incorrect as glucose is a specific type of sugar, not an element found in the composition of carbohydrates.

Correct Answer: A

Rationale: Salmon is the correct answer as it is a rich source of omega-3 fatty acids, specifically EPA and DHA, which are known to be beneficial for heart health. Chicken, spinach, and eggs do not contain significant levels of omega-3 fatty acids compared to salmon. While eggs do contain some omega-3s, the amount is considerably lower than what is found in fatty fish like salmon.

Correct Answer: C

Rationale: Infection is a common manifestation of nephrotic syndrome. This is due to the loss of immunoglobulins in the urine, which weakens the body's immune defenses. Dehydration (Choice A) and uremia (Choice B) can be symptoms of kidney dysfunction but are not specific manifestations of nephrotic syndrome. Low blood lipids (Choice D) is incorrect as nephrotic syndrome typically results in high, not low, blood lipid levels due to the body's attempt to replace lost proteins.

Correct Answer: A

Rationale: The correct answer is A: 'mostly found in animal products.' Saturated fats are primarily found in animal products such as meat, dairy, and eggs. They are typically solid at room temperature. Choice B is incorrect because saturated fats are solid at room temperature, not liquid. Choice C is incorrect because saturated fats do not have double bonds; they have single bonds between carbon atoms. Choice D is incorrect because saturated fats are mainly found in animal products, not vegetable products.

Correct Answer: A

Rationale: Short-chain fatty acids are the preferred fuel for the cells lining the colon. They provide energy and support gut health by serving as a fuel source for these cells. Long-chain fatty acids are not the preferred fuel for colon cells as they are harder to digest and absorb in this part of the digestive system. Amino acids are the building blocks of proteins and not the primary energy source for colon cells. Glucose is the main energy source for most cells in the body, but colon cells prefer short-chain fatty acids.