AIIMS 2018 Physics Earth's Magnetism MCQ Question

Option A is correct because the question does not provide specific numerical values for the variables in the equation $B = \frac{\mu_0}{4\pi} \cdot \frac{2M}{d^3}$, making it impossible to calculate a definitive magnetic field value. Without values for $M$ (magnetic moment) and $d$ (distance), the equation remains theoretical. The other options are marked as N/A, indicating that they also lack relevant information or calculations necessary for answering the question. Understanding the dependence of magnetic field strength on parameters like distance and magnetic moment is crucial in electromagnetism.