In 1998, scientists discovered that the expansion of the universe has been accelerating. What force is causing this phenomena?
dark energy
Hubble's law
the Doppler effect
background radiation

Option A (dark energy) is the right answer.

Explanation:

A hypothetical supplier of power that creates a force that contradicts gravity, which is assumed to have been the catalyst of accelerated universe development. Hypothetically, dark energy counteracts the kinetic energy including its beginning of the globe, meaning that perhaps the multiverse does not have intrinsic curvature, although observational measurements presently indicate.

Some other three choices have no relation to the particular situation. Thus option A would be the right solution.

From a high concentration to a low concentration.

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