单选题 More and more vehicles using cheap fuel, declared scientists at the conference, have left Bangkok's children with body lead levels the world highest.

【正确答案】 C
【答案解析】[解析] 因为the highest在本句中作宾语补足语，且曼谷不是唯一的儿童体内铅含量高的城市，因此应用among the world's highest，C为答案。