By pressing a tiny amount of nitrogen between two diamonds to a pressure of 25 milliion pounds per square inch, scientists not only were able to transform the gas into a solid, but they also created a semiconductor similar to silicon
A.
B. not only were able to transform the gas into a solid but also creating
C. were able not only to transform the gas into a solid but to create
D. were able not only to transform the gas into a solid but also creating
E. were able not only to transform the gas into a solid but they were also able to create
I am surprised by the answer. Is it acceptable to omit " also" in "not only x , but also y" structure.