Suppose Nina decides to see the tamarins. Which result would be a cost?

 - Nina will spend more time walking to the tamarins. They are on the other side of the zoo, but the vultures are close by.
 - Nina will enjoy seeing the tamarins more than she would have enjoyed seeing the vultures.
This result is a cost. It involves giving up or spending something that Nina wants or needs:
Nina will spend more time walking to the tamarins. They are on the other side of the zoo, but the vultures are close by.