<p>The correct answer is <strong>(D) subject</strong>.</p>
<p>In this sentence, the phrase "to approval by the city council" is a prepositional phrase that functions as an adverbial phrase. It modifies the verb "is" and indicates the condition or requirement for the sale of the property. </p>
<p>The word "subject" is an adjective that means "dependent on" or "conditional upon." In this context, it is used to convey that the sale of the property is dependent on or conditional upon the approval of the city council. </p>
<p>The other options are not grammatically correct or do not fit the context of the sentence:</p>
<p>(A) "Subjective" is an adjective that means based on personal opinions or perspectives. It does not fit the context of the sentence because the approval of the city council is an objective requirement, not a subjective one.</p>
<p>(B) "Subjectively" is an adverb form of "subjective." As mentioned above, "subjective" does not fit the context, so the adverb form is also not appropriate.</p>
<p>(C) "Subjecting" is a verb form of "subject" that means to cause someone or something to experience or undergo something. It does not fit the context of the sentence because it does not convey the idea of being dependent on or conditional upon the approval of the city council.</p>