One nation could not have an advantage over other nations.
Answer: Option C
Step-by-step explanation:
The open door policy was the policy which was started by the United States of America in 1899 and 1900. The basic aim of this policy was that all the countries who are going to trade with China would have Equal privileges. No country would be treated better than the other.
This policy was a form of support to the administration of China by the United States of America. These statement of principles gained major popularity in the world when they were started.