For all three categories, no airline achieved the highest ranking of A, which meant optimal carbon efficiency has not been managed yet.

对于所有三个类别， 没有一家航空公司获得 A 的最高排名，这意味着最佳碳效率尚未得到管理。

They are tremendously fuel efficient to bring to market, a fraction of the fuel cost of say, shrimp, and at the very top of the carbon efficiency scale.

让这种鱼上市的燃油经济性极高，比如和虾比，燃油消耗只是个零头， 而且它在碳效率上也是在最前列。