What type of tents become obsolete as more permanent facilities are built?

The correct choice refers to the type of temporary structures that are typically employed for initial housing and support in various operational environments. As more permanent facilities are constructed, the need for these tents diminishes because they are designed for short-term use and can be easily replaced or rendered unnecessary by sturdier, long-lasting infrastructures.

Specifically, the acronym SSS stands for "Small Shelter System," which is utilized in situations where rapid deployment and flexibility are essential. As an area develops and evolves into a more stable environment with permanent buildings and facilities, the transient nature of the Small Shelter System makes it impractical, leading to its obsolescence.

In contrast, the other options represent types of shelters that serve different purposes or are intended for longer-term use. Large Area Maintenance Shelters and Hardback shelters, for example, are designed to provide more substantial protection and can remain in use alongside permanent facilities, while MSS also indicates a form of temporary but relatively larger support that might still be utilized even as permanent structures are added. Thus, the necessary shift to more enduring solutions directly causes the Small Shelter System to become less relevant in environments transitioning to long-term operational setups.