What might be affected by the existence of "dark matter"?

(a) the rate at which the universe is expanding

(b) the ability to observe all existing galaxies

(c) the lifespan of our sun

Many believed that the mass of all the stars, planets and everything that can be observed in the universe comprise only of 20 percent of its total mass. While the dark matter, which is often referred to as the elusive, invisible substance, makes up the remaining 80 percent.

Though the existence of the dark matter is sitll debatable, if proven, it may affect the rate at which the universe is expanding.

A. the rate at which the universe is expanding