Why Is It Not Possible to Use Koch's Postulates to Show

Multiple Choice

Why is it not possible to use Koch's postulates to show that Treponema pallidum causes syphilis?

A) T. pallidum is a Gram-negative organism.
B) T. pallidum cannot be grown in pure culture.
C) T. pallidum causes different diseases in different hosts.
D) Syphilis is a polymicrobial disease; T. pallidum is only one of the causative agents involved in the disease.
E) T. pallidum does not contain a genome.