Correct Answer: D

Rationale: The correct answer is D. A placebo serves as a control for comparison with the treatment group, helping to eliminate bias and ensure the results are due to the treatment itself. Placebos are crucial in research to distinguish the actual effect of the treatment from psychological or subjective factors. Choice A is incorrect because the purpose of a placebo is not related to reducing the cost of the experiment. Choice B is incorrect because while placebos are used in double-blind studies, their primary purpose is not to make the experiment double-blind. Choice C is incorrect because the purpose of a placebo is not to increase the number of participants but rather to serve as a comparison group for the treatment being tested.

Correct Answer: A

Rationale: In managing type 2 diabetes in a child, focusing on increasing physical activity and dietary management is crucial, especially in the initial treatment phase. This approach helps improve insulin sensitivity and overall glycemic control. Initiating insulin therapy immediately is not the first-line treatment for type 2 diabetes in children. Limiting all carbohydrate intake is not advisable as carbohydrates are essential for providing energy and nutrients. Recommending frequent fasting can be harmful and is not a recommended strategy for managing type 2 diabetes in children.

Correct Answer: C

Rationale: The primary goal of managing diabetes mellitus in children is to ensure normal growth and development. This involves maintaining stable blood glucose levels to prevent complications. Option A is incorrect because promoting weight gain is not a primary goal in managing diabetes; rather, the aim is to maintain a healthy weight. Option B is not the primary goal; although it is important to prevent episodes of hypoglycemia, the main focus is on overall management. Option D is incorrect as optimizing blood sugar control is a means to achieve the primary goal, which is ensuring normal growth and development.

Correct Answer: D

Rationale: Glucose is the correct answer as it is the primary source of energy for the brain and nervous system. The brain relies heavily on glucose to function optimally. While protein and fat play essential roles in the body, they are not the primary sources of energy for the brain and nervous system. Carbohydrates, on the other hand, are broken down into glucose, which is then used as fuel by the brain and nervous system.

Correct Answer: A

Rationale: When a parent expresses concern about their child's weight gain, the most appropriate response is to provide guidance on healthy eating and physical activity. This approach promotes healthy weight management and overall well-being. Suggesting restrictive dieting (Choice B) can be harmful, especially for children, as it may lead to unhealthy relationships with food and potential nutritional deficiencies. Recommending increased caloric intake (Choice C) without proper assessment and guidance can exacerbate the issue. Avoiding discussing the issue (Choice D) neglects a critical opportunity to address the parent's concerns and support the child's health.