Treponema Pallidum Is the Bacterium That Causes Syphilis

Treponema pallidum is the bacterium that causes syphilis.The gram-negative spirochete has never been cultured on bacteriological media.Select the statement that most accurately describes this disease-causing microbe.

A) There is no way to perform an epidemiological study on this disease.
B) Koch's postulates cannot be fulfilled for this disease.
C) Because the bacterium cannot be grown, there is no way to characterize the organism as to staining features, biochemical test reactions, molecular testing, etc.
D) There is no satisfactory way to identify the disease without being able to grow it.