The correct answer is (C) A disaster; a sudden tragedy; a violent upheaval, such as an earthquake or extensive flood; a political or social catastrophe.

Cataclysm comes from French cataclysme, Greek Kataklysmos (flood).

Examples of use:

• The recent cataclysm left hundreds dead and thousands missing.
• More than a billion dollars of damage was caused by the cataclysm.