The Term Complex as Used in the M

The term complex as used in the M.tuberculosis complex:

A) means that the identification of the organism is complex and is only performed in large reference laboratories.
B) is used to describe two or more species whose distinction is complicated and of little or no medical importance.
C) refers to a set of organisms that are genetically indistinguishable but are phenotypically different.
D) refers to different subtypes of the bacteria Mycobacterium tuberculosis.