Occam's Razor is a philosophical principle that means the simplest answer is usually correct. So, if you are facing a dilemma with two plausible explanations, the explanation that has the fewest assumptions or, in other words, that is the simplest, is probably the correct explanation.
The principle of Occam's Razor is an overgeneralization, but it often proves true. Test the simple answers first. It may save you a lot of time, effort, and angst.