Which of the following is considered one of the major reasons of Global Warming or heating of Earth’s surface which is at increase these days?

Distance between the Sun and Earth has reduced by about 45,0001(ms. in the last 1000 years.

A big unidentified celestial object is approaching Earth very fast. The radiation from it is making the Earth’s surface warmer

Carbon pollution from fossil fuels traps the Sun’s heat instead of letting it radiate back safely out into space

Sun has become slightly cooler by several degrees centrigrade and is not able to reabsorb the heat radiation back as it used to do earlier

None of these