Answer: Pairwise disjoint and their union is A.
- A Always of equal size in every case
- B Allowed to overlap partially
- C Always exactly two in number
- D Pairwise disjoint and their union is A
Correct answer: D. Pairwise disjoint and their union is A
Explanation: Equivalence classes partition the set: every element lies in exactly one class.
Concept context
Types of relations, equivalence classes, one-one and onto functions, composition, and invertible functions