I would buy my mom house if I blank the game show

The answer is A: won I would buy my mom a house if I won the game show. This sentence is an example of a conditional type 2, which is used to express something unreal, contrary to known facts. And the verb won is not past, but subjunctive, which indicates unreality or improbability. Another example is: If I were you I would visit her. (In truth, I am not you.)