The most accurate response is:
The Qing dynasty faced rebellions and wars after the Treaty of Nanking. This led to its collapse.
After the Treaty of Nanking was signed in 1842, the Qing Dynasty experienced a series of conflicts, including the Taiping Rebellion (starting in 1850), the Second Opium War (1856-1860), and the Boxer Rebellion (1899-1901). These events weakened the dynasty significantly, both militarily and in terms of its legitimacy in the eyes of the populace. Ultimately, this accumulation of internal strife and external pressures contributed to the collapse of the Qing Dynasty and the establishment of the Republic of China in 1912.