Cosmic rays are high-energy particles that originate from outer space, such as the Sun, distant stars, and even distant galaxies. They consist of protons, electrons, and atomic nuclei, with energies ranging from a few million electron volts (eV) to several hundred billion electron volts (GeV). These particles travel at nearly the speed of light and can penetrate through the Earth's atmosphere and reach the surface.



There are three main types of cosmic rays based on their energy levels:

1. Low-energy Cosmic Rays:
- These cosmic rays have energies ranging from a few million to a few hundred million electron volts (MeV).
- They primarily originate from our Sun and are known as solar cosmic rays.
- These rays are relatively low in energy and can be easily shielded by the Earth's atmosphere and magnetic field.

2. High-energy Cosmic Rays:
- High-energy cosmic rays have energies ranging from a few hundred million to several billion electron volts (GeV).
- They originate from a variety of sources within our galaxy, such as supernovae explosions and pulsars.
- These cosmic rays can penetrate the Earth's atmosphere and reach the surface.
- They can cause ionization of atoms in the atmosphere, leading to the production of secondary particles.

3. Ultra-high-energy Cosmic Rays:
- Ultra-high-energy cosmic rays have energies above several billion electron volts (GeV).
- The origin of these cosmic rays remains a mystery, as their sources are still not fully understood.
- They are extremely rare, with only a handful of detections per year.
- These cosmic rays can have significant impacts on the Earth's atmosphere and can produce extensive air showers.



The correct answer to the question is option 'A' - high-energy radiations. Cosmic rays are primarily high-energy particles that can travel vast distances through space and have the ability to penetrate through the Earth's atmosphere. They consist of particles with energies ranging from a few million to several hundred billion electron volts (eV), making them high-energy radiations.