Correct Answer: B

Rationale: The correct answer is B: Ensure strict infection control measures. Children with acute lymphoblastic leukemia (ALL) who are undergoing chemotherapy have compromised immune systems, making them highly susceptible to infections. Implementing strict infection control measures, such as hand hygiene, limiting exposure to sick individuals, and maintaining a clean environment, is essential to prevent infections. Choice A is incorrect because avoiding all physical activity may not be necessary as long as the child's activity level is appropriate. Choice C is incorrect because increasing daily caloric intake is important to support the child's nutritional needs during treatment. Choice D is incorrect because limiting fluid intake is not typically recommended unless specifically advised by the healthcare provider.

Correct Answer: A

Rationale: Frequent urination is a common sign of a urinary tract infection in older children. It is often accompanied by other symptoms such as pain or discomfort. Increased appetite (Choice B) is not typically associated with urinary tract infections. Elevated blood pressure (Choice C) is more commonly linked to conditions like hypertension, not urinary tract infections. Decreased energy levels (Choice D) can be a sign of various health issues but are not a typical symptom of a urinary tract infection.

Correct Answer: C

Rationale: An essential nutrient is a substance that cannot be made in sufficient quantities by the body itself, so it must be obtained from the diet. Choice A is incorrect because essential nutrients are required in specific amounts, not necessarily large quantities. Choice B is incorrect as essential nutrients cannot be synthesized by the body at all. Choice D is incorrect because although essential nutrients may be used in the synthesis of other compounds, that is not the defining characteristic of an essential nutrient.

Correct Answer: A

Rationale: The correct answer is plant fats (Choice A). Fats, including plant fats, provide 9 kcalories per gram, which is more than 4 kcalories. Plant proteins (Choice B) and animal proteins (Choice C) provide 4 kcalories per gram. Plant carbohydrates (Choice D) also provide 4 kcalories per gram. Therefore, Choices B, C, and D are incorrect because they do not yield more than 4 kcalories per gram.

Correct Answer: C

Rationale: When an increase in exercise is accompanied by a decrease in body weight, it demonstrates a negative correlation. This means that as one variable (exercise) increases, the other variable (body weight) decreases. Choice A, 'variable effect,' is vague and does not accurately describe the relationship between exercise and body weight. Choice B, 'positive correlation,' is incorrect because in a positive correlation, both variables would increase or decrease together. Choice D, 'randomization effect,' is unrelated to the scenario described.