A long straight wire along the Z-axis carries a current i in the negative Z-direction. The magnetic vector field B at a point having coordinates (x, y) in the Z = 0 plane is

• A

  $\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi }}\frac{(\mathrm{y}\mathbf{i}-\mathrm{x}\mathbf{j})}{\left({\mathrm{x}}^2+{\mathrm{y}}^2\right)}$

• B

  $\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi }}\frac{(\mathrm{x}\mathbf{i}+\mathrm{y}\mathbf{j})}{\left({\mathrm{x}}^2+{\mathrm{y}}^2\right)}$

• C

  $\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi }}\frac{(\mathrm{x}\mathbf{j}-\mathrm{y}\mathbf{i})}{\left({\mathrm{x}}^2+{\mathrm{y}}^2\right)}$

• D

  $\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{\pi }}\frac{(\mathrm{x}\mathbf{i}-\mathrm{y}\mathbf{j})}{\left({\mathrm{x}}^2+{\mathrm{y}}^2\right)}$