A wire carrying current I has the shape as shown in adjoining figure. Linear parts of the wire are very long and parallel to X-axis while semicircular portion of radius R is lying in Y-Z plane. Magnetic field at point 0 is:

• A. \[\overset{\to }{\mathop{B}}\,=-\frac{{{\mu }_{0}}}{4\pi }\frac{I}{R}\left( \mu \hat{i}\times 2\hat{k} \right)\]
• B. \[\overset{\to }{\mathop{B}}\,=-\frac{{{\mu }_{0}}}{4\pi }\frac{I}{R}\left( \pi \hat{i}+2\hat{k} \right)\]
• C. \[\overset{\to }{\mathop{B}}\,=\frac{{{\mu }_{0}}}{4\pi }\frac{I}{R}\left( \pi \hat{i}-2\hat{k} \right)\]
• D. \[\overset{\to }{\mathop{B}}\,=\frac{{{\mu }_{0}}}{4\pi }\frac{I}{R}\left( \pi \hat{i}+2\hat{k} \right)\]