参考答案

正确答案：the most sustainable solution
the most sustainable solution 解析：根据题干关键词Geoffrey Heal定位到第十一段第四、五句：“I don't care whether companies change for the love of the environment or because of their financial interest."”says Geoffrey Heal…“The most sustainable solution is to have companies responding to financial incentives rather than their own feelings.”可知，Geoffrey Heal说他并不在意公司是为了保护环境还是为了他们自己的经济利益而改变。…最可持续的解决方法就是让公司对经济刺激而不是对他们自己的感情作出回应。