Correct Answer: To shield the Earth from solar wind and cosmic radiation.

Solution : The correct answer is To shield the Earth from solar wind and cosmic radiation.

The Earth's magnetic field serves several important purposes, and its primary role is to protect the planet and its inhabitants from the harmful effects of solar radiation and charged particles. The Earth's magnetic field acts as a shield against the solar wind, a continuous stream of charged particles (mostly electrons and protons) emitted by the sun. Without this protective shield, the solar wind would strip away the Earth's atmosphere over time, as has happened on some other celestial bodies.