To solve this problem, we need to understand the concept of the angle of dip (or magnetic inclination).$\\$The angle of dip is the angle made by the Earth's magnetic field lines with the horizontal plane.$\\$Given:$\\$• At point $A, \delta = +25^\circ. \\$• At point $B, \delta = -25^\circ. \\$Interpretation:$\\$• A positive angle of dip indicates that the magnetic field lines are pointing downward into the Earth.$\\$• A negative angle of dip indicates that the magnetic field lines are pointing upward away from the Earth.$\\$In the Northern Hemisphere:$\\$• The angle of dip is positive because the magnetic field lines point downward into the Earth.$\\$In the Southern Hemisphere:$\\$• The angle of dip is negative because the magnetic field lines point upward away from the Earth.$\\$Analysis:$\\$• At point $A, \delta = +25^\circ,$ indicating it is in the Northern Hemisphere.$\\$• At point $B, \delta = -25^\circ,$ indicating it is in the Southern Hemisphere.$\\$Conclusion:$\\$Therefore, point $A$ is located in the Northern Hemisphere and point $B$ is located in the Southern Hemisphere.$\\$This corresponds to Option 3.