For what purpose can Hong Kong use its designation of "Hong Kong, China"?

The designation "Hong Kong, China" allows Hong Kong to participate in international organizations while being recognized as a part of the People's Republic of China. This designation is significant as it indicates that, although Hong Kong operates with a high degree of autonomy under the "one country, two systems" framework, it is still ultimately a part of China.

In international organizations, this designation enables Hong Kong to take part in certain activities and represent its interests, particularly in areas such as trade, finance, and environmental matters. The unique status allows Hong Kong to engage in discussions and collaborations on global platforms while underscoring its identity distinct from mainland China.

While the other options may seem plausible, they do not fully capture the immediate implications of the designation. Participating in international debates or signing bilateral treaties often requires higher levels of diplomatic recognition or are typically reserved for sovereign states, which is not applicable to Hong Kong's status. Similarly, issuing postal stamps is more of a domestic administrative function and does not serve the purpose of participating in international relations or organizations directly. Therefore, the specific ability to engage with international organizations under the umbrella of "Hong Kong, China" is the most accurate understanding of the use of this designation.