Which among the following explains the origin of the universe?

The correct answer is Option (3) → Big Bang theory

The story of life on earth begins with the story of the universe. NCERT says the universe is almost 20 billion years old and that one theory tries to explain how it began: a singular huge explosion, after which the universe expanded and cooled.

Option (1) Theory of spontaneous generation — Incorrect. This theory was about the origin of life. It held that life came out of decaying and rotting matter like straw and mud. Pasteur dismissed it once and for all.

Option (2) Lamarck's theory — Incorrect. Lamarck’s theory explains the evolution of life forms, which he said was driven by the use and disuse of organs. It says nothing about how the universe began.

Option (3) Big Bang theory — Correct. The Big Bang theory attempts to explain the origin of the universe. After the explosion the universe expanded, the temperature came down, hydrogen and helium formed, and the gases condensed into galaxies.

Option (4) Darwinian theory — Incorrect. Darwin’s theory explains how living forms evolve by natural selection. It deals with life, not with the formation of the universe.

NCERT Extract:
Origin of Life – “… Considering the size of universe, earth is indeed a speck. The Big Bang theory attempts to explain to us the origin of universe. It talks of a singular huge explosion unimaginable in physical terms. The universe expanded and hence, the temperature came down. Hydrogen and Helium formed sometime later. The gases condensed under gravitation and formed the galaxies of the present day universe.”