The Particles in the Rings of Neptune Are Very Dark

The particles in the rings of Neptune are very dark and contain methane ice (CH₄) .They may have become dark due to

A) collisions with small icy particles from the outer reaches of the solar system.
B) forming in a region so far from the sun that only icy particles can exist.
C) forming in a region of the solar nebula where there is an abundance of silicate material.
D) being ejected from volcanoes on the surfaces of geologically active satellites of the planets.
E) radiation from the magnetospheres of the planets interacting with ices in the ring particles.