Final answer:
The utilitarian approach is reflected by farmers acting ethically in the short run to avoid harming others in the long run because it is in their best long-term interests.
Step-by-step explanation:
The approach to deciding ethical dilemmas that is reflected by farmers acting ethically in the short run to avoid harming others in the long run because it is in their best long-term interests is the utilitarian approach. The utilitarian approach focuses on the overall consequence of an action and seeks to maximize utility or happiness for the greatest number of people. In this case, the farmers recognize that allowing the runoff of manure nutrients into a stream that feeds a local lake may provide short-term benefits, but they understand that it can have negative long-term effects on others, such as pollution of the lake and harm to the ecosystem. By acting ethically and avoiding harm to others, the farmers are ensuring the long-term sustainability and well-being of the community and themselves.