in the absence of a designation referred to in paragraph (1)—
(A)#
in the case of a plan maintained by a single employer, such employer,
(B)#
in the case of a plan maintained by two or more employers or jointly by one or more employers and one or more employee organizations, the association, committee, joint board of trustees, or other similar group of representatives of the parties who maintained the plan, or
(C)#
in any case to which subparagraph (A) or (B) does not apply, such other person as the Secretary may by regulation, prescribe.