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Direction: Q.21 to Q.25

Earth's magnetic field is dynamo effect. The circulating electric current in the Earth's core is the origin of the magnetic field. The fluid motion in Earth's outer core moves liquid iron and generates an electric current. The rotation of Earth on its axis causes these electric current to form a magnetic field which extends around a planet. The magnetic field magnitude measured at the surface of the Earth is about a half Gauss.

The magnetic field is extremely important to sustaining life on Earth. Without it, we would be exposed to high amounts of radiation from the Sun and our atmosphere would be free to leak into space. This is likely what happened to the atmosphere on Mars. As Mars doesn't have flowing liquid metal in its core, it doesn't produce the same dynamo effect. This left the plant with a very weak magnetic field, allowing for its atmosphere to be stripped away by solar winds, leaving it uninhabitable. Based upon the study of lava flows throughout the world, it has been proposed that the Earth's magnetic field reverses at an average interval of approximately 3,00,000 years. However, the last' such event, occurred some 7,80,000 years ago.

Read the above passage carefully and give the answer of the following questions:

Which of the following is responsible for Earth's magnetic field?

A) Circulating electric current in Earth's core

B) Rotation of Earth

C) Attraction due to other celestial bodies

D) Solar flares