By the same techniques used for genetically enhancing plants, making them disease- or pest-resistant, researchers have been able to increase the amount of protein in potatoes, sweet potatoes, and tobacco.
A.By the same techniques used for genetically enhancing plants, making them
B.With the same techniques to genetically enhance plants, so that they are
C.Employing the same techniques used to genetically enhance plants so that they are
D.Employing the same techniques to genetically enhance plants, which makes them
E.Employing the same techniques for genetically enhancing plants that make them请各位高手指点!感激不尽
Employing the same techniques for genetically enhancing plants that make them disease - or pest - resistant
这句话里面that 和them的修饰关系是不清楚的
这里的that应该指代前面的plants 而这里的them就应该指代前面的the same techniques
所以这句话的意思就变成了:
采用 相同的技术 来 增强那些 能使得上述技术变得 disease or pest resistant 的 植物..