Two Years After First Being Observed, Astronomers Reported That Saturn's

Two years after first being observed, astronomers reported that Saturn's rings vanished. What happened to them?

A) The old ring system dissipated, and since then a new one has formed.
B) The orbital plane of the rings was seen edge-on, and the rings were too thin to be visible.
C) Most telescopes used hundreds of years ago couldn't adequately resolve the ring system.
D) Astronomers were looking at the wrong planet, leading to the chance discovery of Uranus.
E) They were hidden behind some of Saturn's many moons.