Correct Answer: C

Rationale: To maintain the acidity of urine and potentially prevent urinary tract infections, juices such as apple or cranberry are recommended due to their ability to create an acidic environment in the urinary tract that may help inhibit bacterial growth.

Correct Answer: B

Rationale: Children with brain tumors commonly experience frequent headaches due to increased intracranial pressure. This pressure can result in pain and discomfort, leading to headaches as a common symptom. Other symptoms may include nausea, vomiting, changes in vision, and behavioral changes, but headaches are a prominent feature in children with brain tumors.

Correct Answer: A

Rationale: Glucocorticoids are contraindicated in the treatment of a patient with systemic fungal infection or in patients receiving live vaccines due to their immunosuppressive effects. Glucocorticoids can exacerbate fungal infections by suppressing the immune response. While caution is advised in patients with diabetes mellitus, myasthenia gravis, and glaucoma, the presence of a systemic fungal infection warrants questioning the use of glucocorticoids to prevent worsening of the fungal infection.

Correct Answer: D

Rationale: The 18-month-old child with tachypnea is at the highest risk for dehydration due to increased insensible water loss associated with rapid breathing.

Correct Answer: B

Rationale: Angiotensin II is the most potent compound in the renin-angiotensin-aldosterone system for raising blood pressure. It acts as a powerful vasoconstrictor, leading to increased systemic vascular resistance. Angiotensin II is formed from angiotensin I through the action of the angiotensin-converting enzyme. While renin initiates the cascade by converting angiotensinogen to angiotensin I, it is angiotensin II that exerts the strongest pressor effect.