How Did Large Iron Deposits,called Banded Iron Formations,form

Multiple Choice

How did large iron deposits,called banded iron formations,form?

A) hot water circulates along the margins of a caldera
B) groundwater mixes with seawater in the subsurface
C) magma releases metal-rich fluids that replace reactive rocks
D) an increase in oxygen in Earth's atmosphere caused seas to precipitate beds of iron-rich minerals