What did the Opium Wars between China and Britain indicate regarding China's strength and relationship with the West?
In order to answer this, you need to think about what the Opium Wars were about and what their result was. These were wars that were fought because the British wanted to sell opium to the Chinese while the Chinese government wanted to prevent them from doing so. The British overwhelmingly defeated the Chinese. This gave them the right to sell opium in China. It also gave them the right to get various concessions from the Chinese, allowing the British, for example, to try their own citizens in their own courts rather than making them subject to Chinese law.
So, we have a case in which the British were able to force China to grant them major concessions, including the right to sell narcotics in China. This clearly tells us that China had become much weaker than the West. It tells us that China had essentially become subservient to the West because it could not possibly beat a Western country in any sort of a military conflict. This was a major change from the days in which the Chinese looked down on the West.