What does box 3 of the CMBRE contain?

The correct answer is that box 3 of the CMBRE contains the accessory kit for non-essential components. This box is specifically designed to store additional items that support the functioning and maintenance of the CMBRE system but are not critical for its primary operation. These non-essential components can include various tools and parts that facilitate troubleshooting, installation, or repair, thus enhancing the overall usability and versatility of the CMBRE equipment.

The other options do not accurately reflect the contents of box 3. For instance, TAU and DCSA refer to distinct components or systems rather than items found in box 3. Similarly, while test cables are also important to the overall functioning of various data and communication systems, they are typically found in different locations or boxes within a complete kit or system setup. By understanding the specific purpose and contents of each box in the CMBRE, it becomes easier to effectively manage and utilize the equipment in a practical setting.