What Causes Sinkhole Collapse? Where Is the Cavity That It

Multiple Choice

What causes sinkhole collapse? Where is the cavity that it collapses into,and how does that cavity form?

A) A limestone cavern dissolves out with acid rain; a sinkhole forms when its roof collapses.
B) Soil above a limestone cavern percolates down into the cavern, leaving a soil cavity above. That cavity may collapse to form a sinkhole.
C) An underground river erodes a wide area; a sinkhole forms if its roof collapses.
D) The roof of a gold or copper mine collapses to form a sinkhole.
E) Families of moles or gophers dig large underground chambers that can collapse to form sinkholes.