Final answer:
Pope Gregory VII declared in 1073 that canonization was the only legitimate form of Sainthood, reinforcing the papacy's authority over the matter.
Step-by-step explanation:
The correct answer to the question is B) Pope Gregory VII in 1073. Pope Gregory VII was known for initiating significant reforms in the church and consolidating papal authority. His move to ban simony, the buying or selling of ecclesiastical privileges or church offices, and his conflicts with Holy Roman Emperor Henry IV over investiture, were central to cementing the legitimate power of the papacy over the appointment and management of church officials.
This reform ensured that only the papacy could declare canonization as the official, and legitimate form of recognizing Sainthood, thereby centralizing spiritual authority firmly within the church independent of secular powers.