<p>Despite struggling for the <strong>costly</strong> raw materials, Central Furnishing Inc. still generates high-profit margins.</p>
<p>The correct answer is <strong>(C) costly</strong>.</p>
<p>In this sentence, we need an adjective to describe the raw materials. The word "costly" means expensive or having a high cost. This fits the context of the sentence, as it suggests that Central Furnishing Inc. faces challenges due to the high cost of the raw materials they use. The other options do not work grammatically or contextually:</p><p><span style="font-size: 13.008px;">(A) cost: This is a noun, not an adjective, so it does not describe the raw materials.</span></p><p><span style="font-size: 13.008px;">(B) costing: This is a verb form, which does not fit grammatically in the sentence.</span></p><p><span style="font-size: 13.008px;">(D) costs: This is a plural noun form, which does not fit grammatically in the sentence.</span></p>
<p>Therefore, the correct answer is <strong>(C) costly</strong>.</p>