As shown in the figure, a long straight conductor with semicircular arc of radius $$\frac{\pi}{10}$$ m is carrying current $$I = 3A$$. The magnitude of the magnetic field at the center $$O$$ of the arc is: (The permeability of the vacuum $$= 4\pi \times 10^{-7} \text{ NA}^{-2}$$)

A

6 μT

B

1 μT

C

4 μT

D

3 μT