What is an example of a physical barrier? how might it affect where species are found?

An example of a natural physical barrier would be a mountain. A mountain could separate species of foxes from breeding and thus preventing the creation of a new species of fox.

Ibelieve the answer is relative humidity  because it makes more sense that way. solar flares usually occur in space it doesn't affect the earth, well it could but it wont make a significant damage.  latitude is land it doesnt do anything. prevailing winds, i dont know the correct meaning for this but i doubt that affects the land so it has to be relative humidity.

Enzyme. anything that ends in "ase" is usually an enzyme.