The recommended children's dosage of Keflex is 25 to 50 mg/kg/day in divided doses. The maximum daily safe dosage for a child weighing 42 lb is: Round to the nearest tenth.

(Number Only, do not enter mg, kg, or day with your answer)

The correct answer is choice C: Oral rehydration solution (ORS).

Choice A rationale:

Clear liquids, 1 to 2 ounces at a time, might not be sufficient to adequately rehydrate a child with severe dehydration. Clear liquids lack the necessary electrolytes and glucose content to effectively combat dehydration and replace lost fluids.

Choice B rationale:

Administration of antidiarrheal medication is not the initial step in managing severe dehydration caused by acute diarrhea and vomiting. Antidiarrheal medications can slow down the gastrointestinal motility, which may exacerbate the problem by delaying the elimination of the causative agent and prolonging the dehydration.

Choice C rationale:

Oral rehydration solution (ORS) is the recommended initial intervention for managing severe dehydration caused by acute diarrhea and vomiting. ORS contains the appropriate balance of electrolytes (sodium, potassium, chloride) and glucose to replace lost fluids and electrolytes, thereby helping to rehydrate the child effectively. It is absorbed even when digestion is impaired due to the illness.

Choice D rationale:

Intravenous fluids might be necessary if the child's condition is very severe and oral intake cannot be maintained. However, it's not the first-line intervention. Oral rehydration is preferred whenever feasible because it is less invasive and can be administered even in mild to moderate dehydration cases.

The correct answer is choice B: Pulmonic stenosis, ventricular septal defect, overriding aorta, right ventricular hypertrophy.

Choice A rationale:

Pulmonic stenosis, ventricular septal defect, aortic hypertrophy, left ventricular hypertrophy. This choice is incorrect because it includes "aortic hypertrophy" and "left ventricular hypertrophy," which are not components of the tetralogy of Fallot. Aortic hypertrophy is not a recognized structural defect in tetralogy of Fallot, and left ventricular hypertrophy is not a characteristic feature of this congenital heart condition.

Choice B rationale:

Pulmonic stenosis, ventricular septal defect, overriding aorta, right ventricular hypertrophy. This is the correct choice. Tetralogy of Fallot is characterized by four specific structural defects: pulmonic stenosis (narrowing of the pulmonary valve), ventricular septal defect (hole between the right and left ventricles), overriding aorta (aorta positioned over the ventricular septal defect, receiving blood from both ventricles), and right ventricular hypertrophy (enlargement of the right ventricle due to increased workload).

Choice C rationale:

Aortic stenosis, ventricular septal defect, overriding aorta, right ventricular hypertrophy. This choice is incorrect because it includes "aortic stenosis," which is not part of the tetralogy of Fallot. In tetralogy of Fallot, the stenosis occurs at the pulmonary valve, not the aortic valve.

Choice D rationale:

Aortic stenosis, atrial septal defect, overriding aorta, left ventricular hypertrophy. This choice is incorrect. While "overriding aorta" is present in tetralogy of Fallot, "atrial septal defect" and "left ventricular hypertrophy" are not part of this condition. Atrial septal defects involve a hole between the two atria, not the ventricles, and left ventricular hypertrophy is not typically seen in tetralogy of Fallot.