Which Statement About Accretion Disks Is Not True

Which statement about accretion disks is not true?

A) The primary factor determining whether a white dwarf has an accretion disk is the white dwarf's mass.
B) The gas in the inner parts of the disk travels faster than the gas in the outer parts of the disk.
C) The gas in the inner parts of the disk is hotter than the gas in the outer parts of the disk.
D) Accretion disks are made primarily of hydrogen and helium gas.