The correct answer is (a). Cosmic rays are not electromagnetic waves. They are made of highly energetic charged particles, such as protons and electrons, that travel at speeds close to the speed of light. Cosmic rays originate from outside the solar system, and most of them come from supernova explosions.
(b) Cosmic rays have very short wavelengths, but they are not electromagnetic waves. Electromagnetic waves are waves of energy that travel through space and matter. They are made up of electric and magnetic fields that oscillate at right angles to each other. Cosmic rays, on the other hand, are made up of highly energetic charged particles.
(c) Cosmic rays are made of highly energetic charged particles, such as protons and electrons. These particles are accelerated to very high speeds by powerful cosmic events, such as supernova explosions. When they reach Earth’s atmosphere, they collide with atoms and molecules, producing a shower of secondary particles. These secondary particles can be detected by ground-based instruments.
(d) Cosmic rays do not originate from the Sun. The Sun does emit a stream of charged particles called the solar wind, but this stream is too weak to produce the high-energy cosmic rays that we observe. Cosmic rays are thought to originate from outside the solar system, and most of them come from supernova explosions.