Why Is Physiological Density Sometimes Used by Geographers Instead of Arithmetic

Why is physiological density sometimes used by geographers instead of arithmetic density to describe how many people are in a given area?

A) Physiological density takes into account how the people feel about where they live.
B) Physiological density is used to understand the number of people supported by arable land.
C) Physiological density and arithmetic density mean the same thing.
D) Physiological density takes into account migration patterns.
E) Physiological density is more reliable because it is based on census calculations.