During the Third Century BCE, Which of the Following Was

During the third century BCE, which of the following was the biggest change in the Chinese political state under Emperor Qin Shihuangdi?

A) The Chinese empire widely accepted Buddhism.
B) The Chinese empire became centralized.
C) Emperor Qin Shihuangdi had artisans create elaborate tomb sculptures.
D) Emperor Qin Shihuangdi established civil service exams.