This year community organizers issued a press release to take responsibility for the precipitous reduction of plastic waste in the city, declaring that their advocacy for ordinances mandating that fees be on plastic containers prevent significant amounts of litter

A. mandating that fees be on plastic containers prevent
B. mandating fees on plastic containers is preventing
C. that mandate fees on plastic containers prevent
D. to mandate fees on plastic containers are preventing
E. to mandate fees on plastic containers is preventing

What's wrong with options C and D? Can someone please elaborate?