How is the noncontrolling interest in subsidiary valued at the date of acquisition, following U.S. GAAP?

How is the noncontrolling interest in a subsidiary valued at the date of acquisition, following U.S. GAAP? O a) The noncontrolling interest's share of the book value of the subsidiary at the date of acquisition plus its share of date-of-acquisition goodwill b) The noncontrolling interest's share of the fair value of the subsidiary's identifiable net assets at the date of acquisition c) Fair value at the date of acquisition d) The noncontrolling interest's share of the book value of the subsidiary at the date of acquisition