The best summary of how the Panama Canal contributed to U.S. foreign policy goals in the Caribbean is:
The Panama Canal was an attempt to improve trade between the U.S. and the Caribbean as it connected the Atlantic and Pacific Oceans.
This response highlights the canal's strategic importance for facilitating trade and transportation, which was a key aspect of U.S. interests in the region. While the other options touch on important themes, they do not encapsulate the primary economic motive behind the canal's construction as effectively.