How many vitamins are known to be required in the diet of human beings?

Correct Answer: D

Rationale: The correct answer is D: 13. There are 13 essential vitamins required in the diet of human beings, including vitamins A, C, D, E, K, and the B vitamins. Choice A (5), Choice B (8), and Choice C (10) are incorrect because they do not represent the total number of essential vitamins needed by human beings.

Correct Answer: A

Rationale: The correct answer is A: peer review. Before publication, research findings must undergo peer review, where experts in the field evaluate the validity and significance of the study. Choice B, cohort review, is incorrect as it does not involve the same level of evaluation by experts. Choice C, research intervention, is not a term used to describe the evaluation process before publication. Choice D, double-blind examination, refers to a study design where neither the participants nor the researchers know who is receiving a particular treatment, which is not the same as the peer review process.

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.