Final answer:
The Zhou dynasty's promotion of belief in the Xia dynasty helped them establish legitimacy, consolidate power, and promote national unity through the mandate of Heaven, a key ideological concept sanctioning dynastic succession.
Step-by-step explanation:
The concept of the Mandate of Heaven was used by the Zhou dynasty not only as a justification for its own rule after the overthrow of the Shang dynasty, but also as a way to create a historical narrative that supported the idea of dynastic succession and the righteousness of their own governance. By encouraging belief in the Xia dynasty, the Zhou rulers effectively promoted the belief in a continuous and ordered dynastic cycle, where the heavenly mandate would pass to a new dynasty when the old one no longer governed morally and effectively.
Encouraging belief in the Xia helped the Zhou rulers in several ways: (c) Establishing legitimacy by situating themselves within a lineage of rule sanctioned by heaven, (a) Consolidating power by providing an ideological framework that justified their leadership and subdued opposition, and (b) Promoting national unity by tying together a shared cultural and historical identity rooted in the notion of divinely sanctioned governance.