参考答案

正确答案：A
[答案] A [直接定位] 见第三段“Then they used a modified plant bacterium called Agrobacterium umefasciens to transfer the segment of DNA which manufactures the binding protein into the tobacco plant．”他们然后用一种叫做根瘤土壤杆菌的改变过的植物细菌将能产生结合蛋白的DNA片段移植进烟草。