Which Statement Best Describes the Importance of Banded Iron Formations

Multiple Choice

Which statement best describes the importance of banded iron formations?

A) The rust layers in them serve as evidence for the presence of rocks on early Earth.
B) The rust layers in them serve as evidence for the presence of iron on early Earth.
C) The rust layers in them serve as evidence for the fall of atmospheric oxygen on early Earth.
D) The rust layers in them serve as evidence for the rise of atmospheric oxygen on early Earth.