1. The problem statement, all variables and given/known data I have some problems that I don't know the answer to. A) Does there exist an event space, i.e., probability domain that has exactly one set? B) Is there an event space, i.e. probability domain that has exactly three sets? Is there one that has exactly four sets? C)If D is an event space, i.e., probability domain and each A and B is in D, then A U B is in D. 2. Relevant equations 3. The attempt at a solution I think A is yes, B is no, and C I have no clue. The most important is the WHY. Can someone explain to me why it's yes and no? I'm not sure how to explain it.