In equilateral triangular frame, the is current of 2 A . The side of frame is $\mathbf { 4 } \sqrt { \mathbf { 3 } } \mathbf { ~ c m }$. Magnetic field at center $\mathbf { C }$ is
(A) $\mathbf { 1 0 } \sqrt { \mathbf { 1 0 } } \boldsymbol { \mu } \mathbf { T }$
(B) $3 \sqrt { 10 } \mu \mathrm {~T}$
(C) $20 \sqrt { 3 } \mu \mathrm {~T}$
(D) $30 \sqrt { 3 } \mu \mathrm {~T}$