Answer:
When the Zhou dynasty gained power, it implemented a significant change in the government of China by creating a feudal system. Option A, "It created a feudal system," is the correct answer. The Zhou dynasty's establishment of a feudal system involved dividing the land and granting fiefs to nobles, who in turn owed allegiance and military service to the central Zhou government. This system allowed for a decentralized distribution of power, where the nobles held significant authority within their territories while recognizing the overall supremacy of the Zhou dynasty's central authority. Therefore, the correct answer is A.