What best describes the function of an outer burial container?

The function of an outer burial container is best described as providing protection for the casket in the ground. These containers, which can include grave liners or vaults, serve multiple purposes that enhance the integrity of the burial site. They help prevent the ground from settling over time, which can occur as the soil settles around a casket. By doing so, they maintain the shape of the grave and help ensure long-term stability.

Additionally, outer burial containers provide a barrier against environmental factors, such as water, soil erosion, and pests, which could potentially compromise the casket and its contents. This protective aspect is crucial not only for the preservation of the remains but also for respecting the burial site for future visits by family and friends.

The other options primarily misrepresent the purpose of the outer burial container. For instance, holding ashes pertains to cremation containers rather than burial containers. Serving as a grave marker describes the role of headstones or monuments, and holding personal items of the deceased is not a function of outer burial containers, which are designed primarily for structural and protective purposes rather than storage.