On (A={1,2,3,4,5,6}), (aRb) if and only if (\operatorname{lcm}(a,6)=\operatorname{lcm}(b,6)). Which is the equivalence class of (4)?

Correct answer: ({4})

Step 1: (\operatorname{lcm}(4,6)=12). Step 2: In the given set, only (4) has least common multiple (12) with (6). Step 3: Only elements with the same value lie in one class, so the class is ({4}).