Answer: Set of prime numbers less than 20.
- A Set of students considered tall by some people
- B Set of players considered good by some judges
- C Set of flowers considered beautiful by viewers
- D Set of prime numbers less than 20
Correct answer: D. Set of prime numbers less than 20
Explanation: A set must be well-defined (each element clearly belongs or not). Prime numbers less than 20 is unambiguous.
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