Which of the following factors will not affect a balanced physiology?
a. elevation
b. precipitation type
c. humidity
d. sun exposure

The correct option is B.
A balanced physiology can be affected by elevation because as the altitude change, there will be changes in the surrounding air pressure and this will affect the person's internal system. Sun exposure and humidity will also affect a balanced physiology because, they will affect the amount of water, that is been lost from the body system. 
Precipitation type on the other hand has no effect whatsoever on a balanced physiology.