单选题 The organization had broken no rules, but ______ had it acted responsibly.

【正确答案】 A

【答案解析】[考点] 词义辨析。
[解析] 本题测试倒装句。后半句为倒装句。A项正确。C、D排除。使用so的前提是前面句子必须是肯定句，所以B项错。