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

• A
  $\frac{{\mu _0}I(y\hat i - x\hat j)}{{2\pi ({x^2} + {y^2})}}$
• B
  $\frac{{\mu _0}I(x\hat i + y\hat j)}{{2\pi ({x^2} + {y^2})}}$
• C
  $\frac{{\mu _0}I(x\hat j - y\hat i)}{{2\pi ({x^2} + {y^2})}}$
• D
  $\frac{{\mu _0}I(x\hat i - y\hat j)}{{2\pi ({x^2} + {y^2})}}$