Final answer:
Training schools for nurses in the United States were affiliated with select hospitals.
Step-by-step explanation:
The correct statement about U.S. training schools for nurses established after the Civil War is A) Training schools were affiliated with a few select hospitals.
These training schools were typically affiliated with specific hospitals rather than being independent institutions. The hospitals provided the necessary facilities and resources for the training of nurses. Students would receive practical training alongside experienced nurses in the hospital setting.