Which systems require a "swap"? On what days are they performed?

The correct choice indicates that DRD swaps occur on Monday, Wednesday, and Friday, while TACAN swaps are conducted on Tuesday.

This aligns with typical operational maintenance schedules that are designed to ensure that critical systems undergo regular updates and checks. The frequency of the DRD swaps across three days allows for thorough maintenance and reliability checks, reducing the risk of system failures. By including the TACAN swaps on a separate day, it ensures that while one system is undergoing maintenance, the other can remain operational, thus maintaining overall operational efficiency. Utilizing specific days for different systems reflects a well-structured approach to maintenance, thoughtfully planned to balance system availability with the need for maintenance checks.