If A⊆BA \subseteq BA⊆B and B⊆AB \subseteq AB⊆A, which of the following is true?
A=BA = BA=B
A⊂BA \subset BA⊂B
A∪B=∅A \cup B = \emptysetA∪B=∅
A∩B=∅A \cap B = \emptysetA∩B=∅