Let $R=\left\{\left(P,Q\right)\right|P$ and $Q$ are at the same distance from the origin$\}$ be a relation, then the equivalence class of $\left(1,-1\right)$ is the set

• A

  $S=\left\{\left(x,y\right)|x^2+y^2=1\right\}$
• Correct answer
  B

  $S=\left\{\left(x,y\right)|x^2+y^2=2\right\}$
• C

  $S=\left\{\left(x,y\right)|x^2+y^2=\sqrt{2}\right\}$
• D

  $S=\left\{\left(x,y\right)|x^2+y^2=4\right\}$

Hence, the correct answer is option: 'B'.