Analysis of test questions: The materials in the title emphasize that the total value of China's foreign trade import and export has increased due to the major decision of reform and opening up. Compared with other countries, it is the country with the best economic development. It can be seen that China's economy is constantly developing. So a is correct. The other three options are considered from the perspectives of politics, culture, science and education, so they are inconsistent with the meaning of the question.

Comments: This question has a certain comprehensiveness, which is conducive to guiding students to comprehensively and deeply understand the relevant contents of the textbook, accurately grasp the basic knowledge, and sort out the confusing knowledge points.