Speed limits could be posted where it is common for animals to cross the decrease the number of roadkill around. It is also possible that there will be a decreased speed limit where children are playing nearby so the driver doesn't accidentally hit them. Sharp turns are also a hazard because motorcycle riders could think no other drivers are on the road and speed up, then get hit by a car. Railway crossings also induce a decreased speed limit. So all those are possible options.
To address the agricultural issues, there is a need to develop "cleaner" pesticides. Thus, the answer is letter D. The government had issued different laws and regulations that ensure the pesticides being used are not very detrimental to the human body.