What was the main result of repeated collision and merging in planet formation?

Correct answer: Formation of larger protoplanets from small bodies

The governing concept is accretion, the gradual growth of a body through repeated collisions and gravitational merging. In the young Solar System, dust and rock particles joined to form planetesimals. Continued impacts caused these smaller bodies to combine into increasingly larger objects called protoplanets, which later developed into planets. Therefore, option C is correct. The process did not make planets shine by themselves; planetary light is mainly reflected sunlight. It also did not transform planets into galaxies, which are enormous systems containing stars, gas, and dust. Finally, the Sun remained the central star, not a satellite. Accretion thus explains both the collision process and the increase in planetary size.