The given circuit involves two current-carrying conductors forming a network with a point \(P\) located near them. The magnetic field at \(P\) due to each segment of the circuit can be calculated using Ampère's law and the Biot-Savart law. The total magnetic field at point \(P\) is a summation of the contributions from each segment. The correct expression for the magnetic field at \(P\) is given by:
\[
|B| = \frac{\mu_0 I}{4\pi R} \left(\frac{3}{2} \pi \right)
\]