<p dir="ltr"><span>In this question, the pronoun “It” is a “dummy subject,” not a real subject. The real subject is the noun clause that starts with the blank and continues to the end of the question, “_______ of the two proposals the owner will choose.” Thus, the blank should be filled with a question word to complete the noun clause, especially the question part of it, that is, “________ of the two proposals.” (A) "</span><span>which"</span><span> fits the context and the structure, so it is the correct answer. </span></p><p dir="ltr"><span>(B) "</span><span>whose"</span><span> is incorrect unless the question part is rewritten as “whose proposals.” </span></p><p dir="ltr"><span>(C) "</span><span>what"</span><span> is inappropriate because when used as a question word, it indicates that the options are unlimited, but the words in the question, “of the two proposals,” have indicated that the options are limited instead. </span></p><p dir="ltr"><span>(D) "</span><span>if" </span><span>is incorrect because when used to start a noun clause, it should be directly followed by a noun or noun phrase that acts as the subject of the noun clause, not by a phrase starting with “of.” </span></p>