AIIMS 2019 Physics Magnetic Field due to Current MCQ Question

For the resultant magnetic field at point A to be zero, the magnetic fields produced by the two parallel wires must be equal in magnitude and opposite in direction. Using the formula for the magnetic field due to a long straight current-carrying wire, $B = \frac{{\mu_0 I}}{{2\pi r}}$, where $\mu_0$ is the permeability of free space and $r$ is the distance from the wire, we can set the magnetic fields from both wires equal to each other. Solving for the current $I$ yields a value of 30 A, which satisfies the condition for zero resultant magnetic field. Other options do not yield this balance, making them incorrect.