Genetic engineering sometimes entails plant or animal genes' getting spliced into other species' DNA, either to improve crop yields or for warding off insects or disease.
A. plant or animal genes' getting spliced into other species' DNA, either to improve crop yields or for warding off
B. plant or animal genes that get spliced into the DNA of other species, either for improving crop yields or the warding off of
C. the splicing of plant or animal genes into other species' DNA, to either improve crop yields or to ward off
D. splicing plant or animal genes into the DNA of other species, either to improve crop yields or to ward off
E. splicing of plant or animal genes into the DNA of other species, for either the improvement of crop yields or to ward off


my concern: i can understand that option C is wrong for the BAD parallelism in the construction "either improve crop yields or to ward off"; however, i want to know whether the construction "entails the splicing of plant or animal genes" in option C is also WRONG? i get the feeling that the construction "entails the splicing of plant or animal genes" (complex gerund in option C)is superior to "entails splicing plant or animal genes.." (simple gerund in option D)