Greenpeace has been invited to appraise the environment costs of such an operation.
【正确答案】 C
【答案解析】解析：句意：(保护动物不遭捕猎等的)“绿色和平”组织应邀对这次行动的成本做一个评估。evaluate评估。esteem尊重；意见。appreciate欣赏。approve赞成。