The Basic Law states that the Hong Kong Special Administrative Region can maintain its own system of _________.

The correct answer is that the Hong Kong Special Administrative Region can maintain its own system of governance. This is enshrined in the Basic Law, which serves as the constitutional document for Hong Kong following its return to China. The structure of governance established in the Basic Law allows Hong Kong to operate with a high degree of autonomy, including the separation of powers and the ability to administer local affairs.

The autonomy granted includes the management of the political and legal systems, ensuring that local governance aligns with the principles of "one country, two systems." This principle is intended to provide a framework for governance distinct from that of Mainland China, allowing for legislative, executive, and judicial independence.

While the other options mentioned, such as education, currency, and law enforcement, are indeed areas where Hong Kong has specific frameworks and regulations, they fall under the broader umbrella of governance. Governance encompasses not only the administration of laws and policies but also the overall political structure and democratic processes within which the education, currency, and law enforcement systems operate. Thus, governance is the most comprehensive choice in the context of the Basic Law.