Answer: Symmetric but neither reflexive nor transitive.
- A Transitive but not symmetric
- B Symmetric but neither reflexive nor transitive
- C An equivalence relation
- D Reflexive and transitive
Correct answer: B. Symmetric but neither reflexive nor transitive
Explanation: If l ⊥ m then m ⊥ l, but no line is perpendicular to itself, and two lines perpendicular to the same line are parallel, not perpendicular.
Concept context
Types of relations, equivalence classes, one-one and onto functions, composition, and invertible functions