Which discovery by astronomer vera rubin prove the existence of dark matter?

galaxies exist outside of the milky way.
the expansion of the universe is accelerating.
galaxies spin faster than they should, based on their visible matter.
gas giants form farther from the sun, where temperatures are cooler.

Galaxies spin faster than they should, based on their visible matter proved the existence of dark matter by astronomer Vera Rubin.

Option C

If the galaxy is larger, it spins faster. Some super galaxies have "higher dark matter" compared to smaller spirals. The edge of galaxy moves faster and it will be always closer to the center of the region which leads to the invention of dark matter.

The dark matter is proportional to visible matter amount which makes the rotation speeds proportional to visible mass.  The galaxies which are spiral rotates proportional to visible matter amount like "stars and gas".