单选题 I wrote him a letter to show my appreciation of his thoughtfulness.
【正确答案】 D
【答案解析】句意:我给他写了一封信来表达我对他的体贴的感激。appreciation感激。与gratitude同义。achievement完成;成就。agreement同意;一致。attention注意力;关怀。因此,本题的正确答案为D。