Final answer:
The correct answer to the student's question regarding Europeans living under their own laws in China's ports is (B) Extraterritoriality, which was a result of the 'unequal treaties' signed with Western powers after the Opium Wars.
Step-by-step explanation:
In the context of 19th-century imperialism, Europeans living in their own sections within Chinese ports and being subject to their own laws is an example of extraterritoriality. Extraterritoriality refers to the practice of exempting foreigners from the laws of the country in which they live, allowing them instead to be governed by the laws of their own country. During this period, China was forced to sign what were known as 'unequal treaties' that granted these rights to various foreign nations, starting after the conclusion of the First Opium War and expanding after the Second Opium War.
These practices infringed upon Chinese sovereignty and were a significant aspect of the imperial dominance exercised by Western powers in Asia. The correct answer to the student's question would be option (B) Extraterritoriality.