Answer: A. Post hoc ergo propter hoc.
Post hoc ergo propter hoc is a type of logical fallacy that states "because X happened before Y, then X must be the cause of Y." Therefore, it is a mistake that consists of assuming that correlation implies causation.
In this case, all the team players have worn new uniforms to the games, and they have lost all the games. The fallacy then assumes that because wearing the new uniforms occurred before losing the games, the uniforms must be causing the loses.