GMAT Sentence Correction (SC) | Re: Among lower- paid workers, union members are less likely tha

Consider the following GMATPrep question on same rule:

United States Senator Daniel Inouye was appointed to several posts within the Democratic Party during his first term, that included assistant majority whip and vice-chair of the Democratic Senatorial Committee.
(A) that included
(B) which includes
(C) including
(D) some of which were
(E) among them being

(C) is the correct answer. "including assistant majority whip and vice-chair of the Democratic Senatorial Committee"