Suppose Owen decides to plant the daffodils. Which result would be a cost?
He will save some space. The daffodils will use up less space than the elm tree would have used up. Owen will give up the chance to look at the elm tree. He thinks it would have looked more beautiful than the daffodils.
Owen is deciding whether to plant daffodils or an elm tree in his backyard. He wants to make his backyard more beautiful. But he also wants to leave space for doing fun things.
Before you decide to do something, it is often helpful to list costs and benefits.
Costs are what you give up or spend when you decide to do something. Costs involve giving up things that you want or need.
Benefits are what you gain or save when you decide to do something. Benefits involve gaining something that you want or need.
This result is a cost. It involves giving up or spending something that Owen wants or needs:
Owen will give up the chance to look at the elm tree. He thinks it would have looked more beautiful than the daffodils.