If something is endemic to a region, it is...

When something is described as endemic to a region, it means that it is native to that specific area and occurs naturally there. This term often applies to species of plants or animals that are not found anywhere else in the world, highlighting their unique relationship with the particular environment or ecosystem. This uniqueness indicates that these organisms have evolved in isolation from others, adapting specifically to their local surroundings.

In contrast, the other choices present scenarios that do not capture the essence of being endemic. Being common and widespread globally refers to species or elements that can be found in multiple regions across the world, which goes against the concept of endemism. Occasionally found implies a transient presence rather than a consistent native existence, and being imported from elsewhere clearly denotes a non-native status. Thus, the correct answer encapsulates the idea of something being intrinsically tied to its local habitat.