A Dairy Farmer Has Several Fields Full of Productive, Vigorous

A dairy farmer has several fields full of productive, vigorous pasture including rye grass and clover. However, whenever he feeds his herd on these particular fields his cows seem to lose their balance and stagger, and soon after have reduced appetites and therefore produce less milk. What course of action should the farmer take to address this problem?

A) Aapply an insecticide to kill any tsetse flies laying eggs in the field.
B) Apply a broad-spectrum antibiotic to kill any entero-gastric bacteria present in the field.
C) Apply a monocot-specific herbicide to kill any noxious weeds.
D) Apply a dicot-specific herbicide to kill any herbs or woody seedlings harbouring toxin-producing filamentous fungi.
E) Apply a fungicide to the field to kill any endophytes living in the pasture plants.