Step 1: Understanding the Concept:
The question asks to identify the country associated with the 'Open Door Policy'. This was a significant foreign policy principle related to international trade in the late 19th and early 20th centuries.
Step 2: Detailed Explanation:
The Open Door Policy was a statement of principles initiated by the United States in 1899 and 1900 for the protection of equal privileges among countries trading with China.
The policy aimed to prevent any single nation from monopolizing trade with China, which was being carved into spheres of influence by imperial powers.
While the policy was proposed by the United States, its primary focus and subject was China. It called for an 'open door' to all nations for trade within China.
Therefore, the policy is fundamentally related to China.
Step 3: Final Answer:
The 'Open Door Policy' was a US policy directed at preserving the territorial integrity of and ensuring equal trade opportunities in China. Hence, it is related to China. Option (C) is correct.