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 sue 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 profited-motivated seed companies, the case with most genetically modified crops previously approved for commercial use, but
C. produced not by profited-motivated seed companies, as was the case with most genetically modified crops previously approved for commercial use, but by
D. not produced by profited-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

This is a GMATPrep question.
I selected C because of correct meaning, correct use of as etc.
Can I have some more light on the question from Forum members.