A microbiologist is looking at a sheep blood agar (SBA) plate from a patient who might have been exposed to a biological agent. The colonies are nonhemolytic, large, have a ground-glass appearance, and look like a Medusa's head. On Gram stain, the colonies are large gram-positive rods that seem to have central spores. What is the most probable organism?
A) Bacillus anthracis B) Brucella mallei C) Burkholderia cepacia D) Yersinia pestis