请教prep1--59关于逗号加连词的问题

stellapass

A new genetically engineered papaya was produced not by seed companies who have been
motivated by profit, which was the case with most genetically modified crops previously approved
for commercial use, but university and United States Department of Agriculture researchers who
allowed growers to use it free of charge.
(A) produced not by seed companies who have been motivated by profit, which was the case with
most genetically modified crops previously approved for commercial use, but
(B) produced not by profit-motivated seed companies, the case with most genetically modified
crops previously approved for commercial use, but
(C) produced not by profit-motivated seed companies, as was the case with most genetically
modified crops previously approved for commercial use, but by
(D) not produced by profit-motivated seed companies, which was the case with most genetically
modified crops previously approved for commercial use, but was produced by
(E) not produced by seed companies who have been motivated by profit, the case with most
genetically modified crops previously approved for commercial use, but by
本题选C
无论是在manhattan还是语法笔记当中一直都是在强调说句子中逗号加连词，连词前后句子必须是完整的句子。在这个题当中，我选出来正确答案没有问题，我也知道它是not...but的平行结构，但是对于but后不是完整结构有点想不明白，而且这种情况在OG当中也有出现过，请大家指教~~

清飞扬

题目做下来我的感觉是

svo (and/but) vo  OR  svo (and/but) o

svo, (and/but) svo

lz说的是第二种情况，但是这题是第一种情况，前面的逗号是插入形式，如果去掉就是一个整句的

stellapass

LS总结的真好，豁然开朗哈~