What is a likely reason that the zhou leadership created the theory of the mandate of heaven?

In ancient China “Mandate of Heaven” also known as Heaven’s Mandate was the power given to someone on earth to rule the country by a superior power in Heavens. Zhou leadership changed the theory in their favor to get that power to rule by claiming that the former emperor had used the power for wrong or personal reasons which actually was not permitted to any ruler by the same theory of “Mandate of Heaven”. 

the old way of life was represented by superstition, an angry god, and absolute submission to authority. the thinkers of the age of reason ushered in a new way of thinking. this new way championed the accomplishments of humankind. individuals did not have to accept despair. science and reason could bring happiness and progress. kings did not rule by divine right. they had an obligation to their subjects. europeans pondered the implications for nearly a century. americans put them into practice first.

the answer is:

c. economic output