The sentence that contains a subordinating connection is D, the one that reads as follows: "as a result, we bought a cooler and made sandwiches for our trip back home". A subordinating connection, also known as subordinating conjunction, is a word or phrase that links a dependent clause to an independent clause. "As a result" is a subordinating conjunction that is used to introduce cause and effect relationships.
The topic that would attract readers the most would be B, so that one is the most appropriate answer.
