单选题 In this factory the machines are not regulated ______ but are jointly controlled by a central computer system.

【正确答案】 B

【答案解析】[解析] individually是“单独地”，与后面的jointly相呼应。各项的意思是：independently是“独立地”；irrespectively是“不顾一切地”；irregularly是“不定期地；不规则地”。所以，本题选B。