A charge of 1 C is placed at one end of a non-conducting rod of radius 0.4 m. The rod is rotated in a vertical plane about a horizontal axis passing through the other end of the rod with an angular frequency 2𝜋 × 10^4 rad/sec. The magnetic field at a point on the axis of rotation at a distance 1 m from the center of the path is

A) 5.75 × 10−5 T                  B) 6.88 × 10−5 T                 C) 7.25 × 10−5 T                 D) 8.08 × 10−5 T