Most primates are immune to feline rhinovirus, but a specific group, this being the golden macaques, are highly susceptible to the organism.

(A) a specific group, this being the golden macaques, are highly susceptible to
(B) a specific group, the golden macaques, is highly susceptible to
(C) one group, specifically golden macaques, is highly susceptible of
(D) a specific group, the golden macaques, which are highly susceptible to
(E) a specific group, the golden macaques, which are highly susceptible of

[spoiler]OA-B
IMO-D[/spoiler]