D. Gravity pulled particles of dust and gas together to form planets.
<h3><u>Explanation;</u></h3>
<em><u>The formation of the solar system took place about 4.6 billion years ago when gravity pulled together low-density cloud of interstellar gas and dust. In other words gravity pulled dust and gas particles together to form planets.</u></em>
It is believed that the solar system formed from an explosion that caused a disturbance of cloud of gas and dust in space. The explosion formed waves that squeezed the cloud and dust particles. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula and then planets were formed.
<em><u>Gravity is important as It keeps the solar system together because without it the planets including the earth would be floating around.</u></em>
