Samples of limestone, granite, quartz, and stalactite are exposed to acidic groundwater. All other conditions being equal, which rock would weather most quickly?

A.
the limestone, because the acidic groundwater would dissolve the rock's calcite
B.
the granite, because the acidic groundwater would oxidize the rock's iron
C.
the quartz, because it would absorb the water, increasing the rock's density and placing added pressure on its molecules
D.
the stalactite, because the water would loosen the bonds that hold its molecules togethe