Chaco Canyon, a settlement of the ancient Anasazi culture in North America, had massive buildings. <b> It must have been a major Anasazi center. </b> Analysis of wood samples shows that some of the timber for the buildings came from the Chuska and San Mateo mountains, 50 miles from Chaco Canyon. <b> Only a major cultural center would have the organizational power to import timber from 50 miles away. </b> In the argument given, the two portions in boldface play which of the following roles? ['The first is inferred from another statement in the argument; the second is inferred from the first.', "The first is one of two premises used to support the argument's main conclusion; the second is the other of those two premises.", "The first is the argument's main conclusion; the second is a premise used to support that conclusion.", "The first is a premise used to support the argument's main conclusion; the second is a premise used to support another conclusion drawn in the argument."]