Answer:
Cardiovascular system
Step-by-step explanation:
A vascular surgeon operates on the various vessels found within the body in order to treat vascular diseases and conditions. This would include the blood vessels as well as those circulating lymph fluid. The system that is closest associated with these structures is the cardiovascular system.
An endocrine surgeon specializing in the endocrine system would perform its surgeries. A cardiothoracic surgeon operates on both the cardiovascular and pulmonary systems. Procedures of the reproductive system are likely performed by a plastics specialist. The surgeons of these systems may change based on the conditions affecting them as well.