weapon of mass destruction

Select one of the four primary categories of terrorist hazards (Chemical, Biological, Radiological/Nuclear, Explosives). Provide a history of its use as a weapon of mass destruction (WMD); describe how it is made and dispersed, signs and symptoms of its use; circumstance where it would be the weapon of choice; actions the public can take to prepare for such an attack; Cite an incident where the hazard was recently used.