What Is the Biggest Problem with Selecting a Site for a Preserve

What is the biggest problem with selecting a site for a preserve?

A) There is always a conflict about use of land set aside for preservation.
B) Making a proper selection is difficult because the current environmental conditions of almost any site may change in the future because of climate change or other factors.
C) Keystone species are difficult to identify in potential preserve sites.
D) Only lands that are not useful to human activities are available for preserves.
E) Most of the best sites are inaccessible by land transportation, so making roads to them is often prohibitively expensive.