What type of alternate site can be described as a "data center in a box" and is commonly used by the military?

The correct answer describes a mobile site, which is characterized by its capability to serve as a flexible and portable data center. This type of site consists of equipment and hardware that can be easily transported to different locations to provide immediate operational capability in the event of a disaster or outage. The concept of a "data center in a box" emphasizes the idea that all necessary components are packaged together for quick deployment, which is particularly beneficial in military operations that often require mobility and rapid response.

Mobile sites are equipped with essential infrastructure to maintain functionality and can be set up in various environments, making them ideal for situations where traditional, permanent data centers may be compromised or impractical to use. This distinct feature sets mobile sites apart from other alternate site options, which may not offer the same level of portability or immediate readiness.