Which corps has a significant number of personnel serving in active and reserve roles exceeding 4,200?

The Nurse Corps indeed has a significant number of personnel serving in both active and reserve capacities that exceed 4,200. This branch of the military is essential for providing nursing care and support within medical facilities, alongside delivering critical health services in various operational environments. The Nurse Corps is responsible for the health and well-being of service members, as well as their families, highlighting the critical role that nurses play in military medicine.

In contrast, while options such as the Medical Corps, Dental Corps, and Medical Service Corps also have dedicated personnel, their numbers may not match or exceed the figures associated with the Nurse Corps in this context. Each of these corps has its own responsibilities and focuses, but in terms of sheer personnel numbers, the Nurse Corps stands out as having a larger active and reserve presence.