The Canton System, which limited foreign influence by confining all foreign merchants to one port city, could be found where?

China

Explanation:

At that time, many of western traders brought in Drugs such as opium into China. This made the government took a precaution to limit the citizen's exposure to western influence. This is why the Canton system was crated.

Before Western's goods can be sold in china, it has to be transported into Canton port and confined in that port. When the goods' were there, the Government will carefully each products and take control over product's distribution.

the correct labels are as follows:

a: yellow river

b: himalayan mountains

c: north china plain

d: taklimakan desert