The magnetic compass magnets are acted on by the horizontal component of the Earth's total magnetic force. This magnetic force is GREATEST at the __________.

Correct Answer: Option B — magnetic equator

The horizontal component of the Earth's magnetic force is the directive force that aligns the compass needle. This force is strongest at the magnetic equator, where the magnetic lines of force are parallel to the surface, and decreases to zero at the magnetic poles where the lines are vertical.