Suppose Isabelle decides to see the storks. Which result would be a cost?
A: Isabelle will enjoy seeing the storks more than she would have enjoyed seeing the cranes.
B: Isabelle will spend more time walking to the storks. They are on the other side of the zoo, but the cranes are close by.
This result is a cost. It involves giving up or spending something that Isabelle wants or needs:
Isabelle will spend more time walking to the storks. They are on the other side of the zoo, but the cranes are close by.