A Caldera Is

A caldera is

A) A topographically low area that results from the collapse of a volcano after its magma chamber empties or removal of the top of a volcano during an explosive eruption.
B) An alternate name for boiling mud pots in thermally active areas.
C) Not associated with andesitic or rhyolitic volcanism, but only with basaltic volcanism.
D) Only preserved for short periods of time, so that ancient calderas do not exist.