Suppose Kurt decides to plant the magnolia tree. Which result would be a cost?
Kurt will get to look at the magnolia tree. He thinks it will look more beautiful than the lilacs would have looked. The magnolia tree will use up more space than the lilacs would have used up.
Kurt is deciding whether to plant lilacs or a magnolia 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 Kurt wants or needs:
The magnolia tree will use up more space than the lilacs would have used up.