If $\mathrm{R}=\left\{\left(\mathrm{x},\mathrm{y}\right)|\mathrm{x}, \mathrm{y}\in \mathrm{z}, {\mathrm{x}}^2+{\mathrm{y}}^2\le 4\right\}$ is a relation in Z, then domain of R is

• A

  $\left\{0, 1, 2\right\}$

• B

  $\left\{0, -1, -2\right\}$

• C

  $\left\{-2, -1, 0, 1, 2\right\}$

• D

  None of these