In a move that surprised many political analysts, Republicans were forced to yield to conservative Christians demanding that they should modify their party platform to reflect public concerns about social issues, including abortion.

A. demanding that they should
B. demanding it to
C. and their demand to
D. who demanded that it
E. who demanded it to

OA D


Does anyone agree with the OA? I chose A because I thought the antecent "Republicans" is plural, so we whould use a plural pronoun.
My understanding says that "republicans" is the plural of "republican", rather than "a group of republican people".

Thanks!