In which ways do sinkholes form?
A. Limestone is dissolved by rainwater, the bedrock surface lowers, and groundwater that is flowing in the passages below washes away the soil.
B. A roof of an already formed cavern collapses under its own weight Lakes with mildly acidic water dissolve the limestone beneath them, leaving behind sinkholes.
C. Limestone is dissolved by rainwater, and the bedrock surface lowers.
D. A stream with mildly acidic water continually cuts down into the limestone until it exposes an underground cavern.
