What is one benefit of using controls in an experiment?

Correct Answer: D

Rationale: The correct answer is D. Controls in an experiment ensure that the subjects are similar in all respects except for the treatment being tested. This allows for a fair comparison between the treatment group and the control group. Choice A is incorrect because the size of the groups is not the primary benefit of using controls. Choice B is incorrect as blinding, not controls, refers to subjects not knowing about the experiment. Choice C is incorrect as it pertains more to randomization than the use of controls.

Correct Answer: D

Rationale: The correct answer is D. Nutrient recommendations are designed to meet the needs of most healthy people, providing guidelines for a balanced diet. Choice A is incorrect because while nutrition plays a crucial role in health, it is not the only factor influencing it. Choice B is incorrect as nutrient needs vary based on factors like age, gender, activity level, and health status. Choice C is incorrect because all nutrients are essential for different bodily functions, and none can be deemed universally more important than others.

Correct Answer: B

Rationale: A positive correlation between two variables indicates that they move in the same direction. This means that as one variable increases (or decreases), the other variable also increases (or decreases). Choice A is incorrect because correlation does not imply causation; it only shows a relationship between variables. Choice C is incorrect as it describes a negative correlation where variables move in opposite directions. Choice D is incorrect as a positive correlation implies a relationship between the variables.

Correct Answer: D

Rationale: The correct answer is D: Fiber. Macronutrients are nutrients required by the body in larger amounts, and they include carbohydrates, proteins, and fats. Fiber is a type of carbohydrate that falls under this category. Vitamin C (choice A) is a water-soluble vitamin, Iron (choice B) is a mineral, and Calcium (choice C) is also a mineral, not a macronutrient. Therefore, Fiber is the only macronutrient listed in the choices.

Correct Answer: B

Rationale: The correct answer is B: 'To promote overall health and reduce the risk of chronic diseases.' Dietary guidelines aim to improve public health by providing recommendations on dietary patterns and nutrient intake. While ensuring food safety and sanitation (choice A) is important, it is not the primary purpose of dietary guidelines. Preventing foodborne illnesses (choice C) is more related to food safety practices rather than dietary guidelines. Recommendations for physical activity (choice D) are important for overall health but are separate from dietary guidelines, which primarily focus on nutrition.