Detailed Analysis:
This question tests the difference between opinion and fact. An opinion expresses personal feelings or judgments, while a fact is information that can be proven true.
Option A: The Osage reservation is in Oklahoma—This is a geographical fact that can be verified.
Option B: People loved to watch Maria dance—The word "loved" expresses the audience's subjective feeling, making this an opinion.
Option C: Maria started a ballet school—This is something she did, a verifiable fact