A. maintaining ecological balance B. to maintain the balance ecologically C. maintain the balanced ecology D. balance ecological maintenanceĐoạn văn60/83Mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 60 to 65. maintaining ecological balance to maintain the balance ecologicallymaintain the balanced ecology balance ecological maintenanceGiải thíchChọn đáp án A