Bacillus anthracis can cause infection via three different portals of entry. The ID50 of cutaneous anthrax is 10 to 50 endospores, whereas inhalation anthrax requires 10,000 to 20,000 endospores, and gastrointestinal anthrax requires 250,000 to 1,000,000 endospores. Which statement best describes a conclusion that can be drawn based on this information?
a. Exposure to a small number of endospores (fewer than 1000) is most likely to result in gastrointestinal anthrax.
b. Cutaneous anthrax is rarely observed when cases across the population are monitored
c. The portal of exit impacts the infectious dose needed to cause infection at the portal of entry.
d. Equal numbers of cutaneous, inhalation and gastrointestinal anthrax infections are observed in human hosts.
e. It is significantly easier to be infected with cutaneous anthrax as compared to other forms of anthrax.