求教885section 20-19

19.   As the etched lines on computer memory chips have become thinner and the chips’ circuits more complex, both the power of the chips and the electronic devices they drive have vastly increased.

(A) the chips’ circuits more complex, both the power of the chips and the electronic devices they drive have

(B) the chips’ circuits more complex, the power of both the chips and the electronic devices they drive has

(C) the chips’ circuits are more complex, both the power of the chips and the electronic devices they drive has

(D) their circuits are more complex, the power of both the chips and the electronic devices they drive have

(E) their circuits more complex, both the power of the chips and the electronic devices they drive have

B的结构是这样分析的吗？（B）the circuits (have become) more complex; the power……has，不太明白这个句子的结构，they究竟指代什么？

谢谢！

B的结构是这样分析的吗？（B）the circuits (have become) more complex; the power……has

Yes, that's correct.

they究竟指代什么？

the chips