If A union B = an empty set which of the following are true? (give all correct choices)
a. A is a proper set of B
b. B is a proper set of A
c. A intersection B = an empty set (correct)
d. A = an empty set (Correct)
e. B = an empty set (Correct)
Plese let me know if I have picked all the correct choices and if not explain why, because my textbook does not explain this very well.