Answer:
b.the agriculter adjustment act
Explanation:
These people became wealthy mostly because of efficient trade between countries. Trading was an important factor back then, and your key word is COASTAL, meaning they are by a sea (aka trading routes). So the answer is trading between countries.
The Molasses Act of March 1733 was an Act of the Parliament of Great Britain (citation 6 Geo II. c. 13), which imposed a tax of six pence per gallon on imports of molasses from non-English colonies. Parliament created the act largely at the insistence of large plantation owners in the British West Indies.