A. marks a major social, economic, or political shift.
Explanation:
A turning point is the name given to a moment in history when a major change or shift happens. This is usually decisive in nature, and forever alters the events that derive from it. The term is most often used by historians.
The concept of turning point is usually applied to positive social, economic or political changes. For example, the invention of the printing press can be seen as a turning point in the cultural history of Europe, as it positively changed society in a significant way.
