Base on the question where as asking to complete the passage and base on my research and further investigation, One of the way to develop a main idea for the advertisement is to conduct product research. I hope you are satisfied with my answer and feel free to ask for more if you have question and further clarification
a: the government created the system on its own.
China originally planned to develop to what it called a Golden Shield surveillance system giving easy access to local,regional and national records of each citizen.
I think it’s a c then b for the third