Final answer:
Increased blood pressure in the upper extremities is the expected finding in an infant with coarctation of the aorta due to the obstruction of blood flow from the heart to the lower body.
Step-by-step explanation:
A nurse caring for an infant with coarctation of the aorta should expect to find increased blood pressure in the upper extremities. Coarctation of the aorta causes a narrowing in the aorta, which can lead to obstruction of blood flow from the heart to the lower part of the body.
This results in higher blood pressure above the constriction, namely in the arms and upper body, while the blood pressure in the lower extremities tends to be lower due to the reduced blood flow. Therefore, the expected finding is increased blood pressure in the upper extremities, making option (a) the correct answer.