<p dir="ltr"><span><span>The question is a complex sentence. The main clause is “The customers were told something,” followed by a noun clause that ends with an adverb clause, “that no reservations could ______ on weekend nights because the restaurant was too busy.” </span></span></p><p>Let’s focus on the noun clause “that no reservations could ______ on weekend nights because the restaurant was too busy.” Firstly, the blank should be filled with the basic form of a verb since it follows an auxiliary verb. Thus, (A) "will be made" and (D) "makes" are eliminated. </p><p dir="ltr"><span><span>(B) "</span><span>make"</span><span> is used in an active voice, while (C) "</span><span>be made"</span><span> is in a passive voice. Since reservations are made instead of making something else, the correct answer is (C) "</span><span>be made"</span><span>. </span></span></p>