Answer: 4.
- A 2
- B 4
- C 6
- D 8
Correct answer: B. 4
Explanation: Symmetric difference = {1, 2, 5, 6}, which has 4 elements.
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