Answer:
d. “Researchers' estimates of the actual number vary from three hundred to six thousand, but everyone knows that ads are everywhere.” (paragraph 1)
Explanation:
Coordinating conjunctions are a type of conjunction that joins two elements in a sentence that are equal in importance and structure. There are seven: for, so, or, nor, and, for, and but. They are often used to give equal emphasis to two main clauses. Option d is the correct answer because it uses the coordinating conjunction “but” to connect the two independent clauses and give equal emphasis to both of them.