What is the radiological appearance of brown vs black pigment stones?
Options:
a) Brown pigment stones appear as radiolucent on plain radiographs, while black pigment stones appear as radiopaque.
b) Brown pigment stones appear as radiopaque on plain radiographs, while black pigment stones appear as radiolucent.
c) Both brown and black pigment stones appear radiolucent on plain radiographs, but brown stones have a mottled appearance.
d) Both brown and black pigment stones appear radiopaque on plain radiographs, but black stones have a more homogeneous appearance.