Why Is It Believed That the Rings of Saturn Could

Why is it believed that the rings of Saturn could not have formed at the same time as the planet itself formed?

A) Over time, the solar wind should have blown away the particles in the rings.
B) The particles in the rings should eventually fall into the planet, in a time much shorter than the age of the planet.
C) The rings are made of ice particles, which would have been vaporized by the heat released as Saturn formed.
D) The outer planets do not have enough mass to hold onto the rings.