Because of what scientists have learned about monoculture, they are: a not pushing for a change in farming. b asking for legislation mandating gmos. c suggesting ways to protect food supplies. d telling farmers they need to grow fewer kinds of crops.

Option C, suggesting ways to protect food supplies

Explanation:

Monoculture is the practice in which a farmer grows same crop year on year on the same land. Due to this practice, the essential nutrients with in the soil get exhausted over a period of time and hence the crop produce ultimately fall down.  

Also in order to replenish the lost nutrient, lot of fertilizers are used which further degrade the soil quality.  

Due to these issues, monoculture leads to the reduction in food supplies.  

Hence, option C is correct.