Much safer vs. safer

Recent improvements in technology, such as lighting that mimics the pattern and intensity of
natural sunlight, have made working night shifts much safer and more productive.
A. have made working night shifts much safer and more productive
B. have made those that work night shifts safer and more productive
C. has made it safer and more productive to work at night
D. has increased the productivity and safety of working at night
E. had made working at night more safer and increased productivity