Concept:The angle of dip (or magnetic inclination) is the angle that Earth’s magnetic field lines make with the horizontal. At the magnetic poles, the field is vertical.Explanation:At the magnetic poles, the magnetic field lines enter or exit the Earth vertically. Therefore, the dip angle is 90∘. At the magnetic equator, the field is horizontal, so dip is 0∘. A dip needle at a magnetic pole stands straight up and down.Answer:C. 90∘