Answer: every set.
- A every set
- B no set
- C only itself
- D only the universal set
Correct answer: A. every set
Explanation: By convention, the empty set is a subset of every set.
A Venn diagram makes set identities visual: A∪B is everything inside either circle, A∩B is only the overlap, and the region outside both circles represents the complement of their union - directly illustrating De Morgan's law (A∪B)′ = A′∩B′.
Concept context
Types of sets, operations (union/intersection/complement), relations, and types of functions with domain and range