Correct Answer - Option 4 : All are correct
The correct answer is All are correct.
The three main theories put forward to explain the origin and evolution of the universe are:
The Big Bang Theory
The Steady-State Theory
The Pulsating Theory
The Big Bang Theory:
Le Maitre and Gammow proposed this theory.
According to this theory, at the beginning of the universe, the whole matter of the universe was once concentrated in an extremely dense and hot (~10 12K) fireball. Then about 20 billion years ago a vast explosion (big bang) occurred.
Steady State Theory:
Bondi, Gold and Fred Hoyle developed this theory.
According to this theory, the number of galaxies in the observable universe is constant and new galaxies are continuously being created out of empty space, which fill up the gaps caused by those galaxies, which have crossed the boundary of the observable universe.
According to this theory, the universe is supposed to be expanding and contracting alternately i.e. pulsating. At present, the universe is expanding.
According to pulsating theory, it is possible that at a certain time, the expansion of the universe may be stopped by the gravitational pull and they may contract again.