The correct answer is A. The expansion of international trade.
Step-by-step explanation
In the photographs you can see two photographs of Hong Kong, the first is from 1910 and the second from 2000. The first photograph shows the coast of Hong Kong with few buildings and boats, while the second photograph shows large buildings and boats. This difference between the two photographs denotes that there was great growth in the city. Hong Kong's growth is because it is a special administrative region that has a free market economy that has allowed this city to be at the epicenter of world trade and economy. Therefore, the correct answer is A. The expansion of international trade.