A wire carrying current `I` has the shape as shown in the adjoining figure. Linear parts of the wire are very long and parallel to X-axis while semicicular portion of radius `R` is lying in `Y-Z` plane. Magnetic field at point `O` is

Options

A. `vec(B) = (mu_(0))/(4pi)(I)/(R) (pi hat(i) + 2 hat(k))`
B. `vec(B) = - (mu_(0))/(4pi)(I)/(R) (pi hat(i) - 2 hat(k))`
C. `vec(B) = - (mu_(0))/(4pi) (I)/(R)(pi hat (i) + 2 hat(k))`
D. `vec(B) = (mu_(0))/(4pi)(I)/(R) (pi hat(i) - 2 hat(k))`

Answer

C