Which of the following sets of characteristics describes the highest level of threat potential from biological weapons?

A) a waterborne toxin that is easily introduced into public water supplies and does not replicate in humans
B) a pathogen of livestock transmitted by contact with infected animals but not infected people
C) a human pathogen easily produced as an aerosol and transmissible by respiratory aerosols
D) a pathogen of wheat that could be delivered using crop dusters
E) a microbe that can be introduced into food during packaging and withstands refrigerator temperatures but not typical cooking temperatures