Basically all of the choices given are failure of negative feedback mechanisms to maintain homeostasis. The correct option among all the options that are given in the question is the last option or option "E". I hope that this is the answer you were looking for and it has come to your help.
An area with unifying characteristic is called as a region. The region is a broad geographic area, which is differentiated from other because of the similar features. In a region one or more than one types vegetational climax might be present. It is the continuous and extensive part of the surface. The area in a region is indefinite.
Hence, the given blank can be filled with region.
