At which place Earth’s magnetic field becomes horizontal?

1. Magnetic meridian
2. Magnetic equator
3. Geographical pole
4. Tropic of Cancer

The magnetic equator is defined as the line around the earth where the magnetic field is horizontal, or parallel to the earth’s surface. It does not circle the earth as a smooth line like the geographic equator, but instead it meanders north and south.

It is a line connecting all points on the earth's surface at which a magnetic needle balances horizontally without dipping.

The correct option is B.