Suppose Mateo decides to plant the geraniums. Which result would be a cost?

 - He will save some space. The geraniums will use up less space than the magnolia tree would have used up.
 - Mateo will give up the chance to look at the magnolia tree. He thinks it would have looked more beautiful than the geraniums.
This result is a cost. It involves giving up or spending something that Mateo wants or needs:
Mateo will give up the chance to look at the magnolia tree. He thinks it would have looked more beautiful than the geraniums.