Answer: is an element of.
- A is an element of
- B is a subset of
- C is the union of
- D is the intersection of
Correct answer: A. is an element of
Explanation: a ∈ A means a is an element (member) of the set A.
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