I find that the best answer is the following one:
c. determined by factors outside our control
For example, even though life is very hard in the very hot and the very cold regions, we can't control it: so this is an example of a physical environment that is hard to control.
In comparison, it is often easier to describe than our social environment.
True, if it's absolutely frozen <span />
I need more context in order to properly respond to this.
