In intestinal diseases, the infectious dose of ______ is quite high, while the infectious dose of a shigella species is lower because ______.
a) Cholera, of the resistance of Shigella to stomach acids
b) Shigella, of the toxin produced by Shigella that is potent even in small quantities
c) Cholera, of the ability of Shigella to multiply rapidly in the gut
d) Shigella, of the high susceptibility of the intestine to Shigella infection
