Banded iron was formed when oxygen first entered the atmosphere when?

Banded iron was formed when oxygen first entered the atmosphere when?

Banded iron was formed when oxygen first entered the atmosphere when?




A 2.4 million years ago
B. 24 million years ago
C. 240 million years ago
D. 2.4 billion years ago
E. 24 billion years ago
F. 240 billion years ago


Answer: D