Why Would Cosmologists Expect the Rate of Expansion of the Universe

Multiple Choice

Why would cosmologists expect the rate of expansion of the universe to be slowing down?

A) The gravitational pull of all objects in the universe on each other would lead to slowdown.
B) All expansions after explosions naturally slow down with time.
C) Galaxies feel a kind of friction as they move through space, which slows them down.
D) The greater the distance between two objects (such as galaxies or superclusters) , the harder it is to push them farther apart.