单选题 Wealthy nations have fallen far behind on their aid ______ to the world's poor.
A. commitments B. engagements C. responsibilities D. applications

【正确答案】 A
【答案解析】[解析] 根据句中“援助世界贫困地区的承诺”可知，只有A项符合题意。commitments 意为“委托事项，许诺，承担义务”。根据题意可知，A项为正确答案。