The magnetic field a the origin due to a current element placed at a position is


According to Biot-Savart law:
The magnetic field due to a current element is given as
Where,

i is the current,


is the length element vector,


is the vector joining the required point and the length element,


μ0 is the permeability of vacuum and μ0 = 4π × 10-7 TmA-1.
Also, by vector properties: A× B = -(B× A)
Thus,
Thus, options (A) and (B) are the correct options

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