Answer:
making China an important trade partner
Step-by-step explanation:
In late 19th century, many western countries fight for the exclusive rights to trade with China.
Since the reward was very lucrative, the western countries were willing to go into an all out war with one another for the exclusive rights.
To prevent this, John Hay proposed an open door policy. This policy allowed colonial powers to trade with China on equal terms so all of them can get some benefits from trading relationship with China. This policy effectively made china became an important trade partner for many Western countries.