His writing depicts this changing world and the increasing cultural diversity of the United States.

【正确答案】 C

【答案解析】 名词词义辨析。在选项中，variety(多样化；种类)与diversity相似。故答案为C。conflict“争论，冲突，斗争”；refinement“精致，文雅”；movement“运动，活动”。