Final answer:
Taizu's military regained control over Central China, as was common for Chinese dynasties seeking to consolidate and expand their influence in surrounding territories. The option (D) is correct.
Step-by-step explanation:
Taizu's military efforts were focused on consolidating power in various regions, including the successful regain of control over Central China, which allowed for the expansion of his influence. As for the influence and control over other regions during different times in Chinese history, the Chinese military was later involved in Tibet as well, with armies taking control of Lhasa. The Tang Dynasty made significant advancements in Central Asia, Manchuria, Vietnam, and Tibet, showcasing the long history of Chinese expansion and consolidation.
Historical events such as the establishment of the People's Republic of China have led to diplomatic and military actions in regions like Tibet, indicating the area that Taizu's military regained control over was d) Central China.