Two wires AO and OC carry equal currents i as shown in Fig. One end of both the wires extends to infinity. Angle AOC is `alpha`. The magnitude of magnetic field is point P on the bisector of these two wires at a distance r from point O is
A. `(mu_(0)i)/(2pir)cot((alpha)/(2))`
B. `(mu_(0)i)/(4pir)cot((alpha)/(2))`
C. `(mu_(0)i)/(2pir)((1+cos(alpha)/(2)))/(sin``((alpha)/(2)))`
D. `(mu_(0)i)/(4pir)sin((alpha)/(2))`