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 [2002S]
a. 2π(x2+y2)μ0I(yi^−xj^)
b. 2π(x2+y2)μ0I(xi^+yj^)
c. 2π(x2+y2)μ0I(xj^−yi^)
d. 2π(x2+y2)μ0I(xi^−yj^)