When Eyjafjallajökull Erupted in March 2010, Ash Plumes Drifted Southeast

When Eyjafjallajökull erupted in March 2010, ash plumes drifted southeast over Europe and, as a result, the controlled airspaces over many European countries were closed to air traffic, stranding thousands of people worldwide.Why would flying a commercial jet through a cloud of volcanic ash be dangerous?

A) Ash can impede visibility if thick enough.
B) Hot ash will cause the plane to catch fire.
C) Abrasion of windows and engine parts from ash.
D) Engines can be clogged by ash.
E) Ash impairs visibility, clogs engines, and abrades engine parts.