Answer:
The correct answer is dark energy.
Explanation:
The force, which is considered to be causing the expansion of the universe is termed as the dark energy. The far way galaxies seem to be moving apart from each other at high speed, the concept is that the universe is getting large and large since the time of Big Bang.
The expansion of the universe is taking place at a greater rate. It is believed that there is something there in the vacant space, which is giving a repulsive force and causing the universe to expand. This is known as dark energy.
