单选题 A child, age 4, is admitted with a tentative diagnosis of congenital heart disease. When assessment reveals a bounding radial pulse coupled with a weak femoral pulse, the nurse suspects that the child has
A. patent ductus arteriosus.
B. coarctation of the aorta.
C. a ventricular septal defect.
D. truncus arteriosus.

【正确答案】 B

【答案解析】Coarctation of the aorta causes signs of peripheral hypoperfusion, such as a weak femoral pulse and a bounding radial pulse. These signs are rare in patent ductus arteriosus, ventricular septal defect, and truncus arteriosus.