Abasic principle of chinese government, which allows a revolution to overthrow and replace a corrupt ruler, is called

Explanation:

This is a Chinese political and religious doctrine. This was used to justify the ruler power, it was said that He was the Son of Heaven. In case that the ruler was overthrown, this was interpreted by people as no worthy of Heaven's power. Also, natural disasters, lacking of goods, all these was justified as a Heaven's punishment.

So, at the end, Chinese society was unified with religious doctrines.

the use of email to replace slower surface mail.

c is the correct answer for this question.