Rational Equations

The equivalence relation means that both and leave the same remainder when divided by 5. We are tasked with finding the equivalence class of 1. The equivalence class of a number is the set of all numbers that give the same remainder when divided by 5. For the number 1, we check all numbers that give a remainder of 1 when divided by 5: Thus, the equivalence class of 1 is . Therefore, the correct answer is option (B).