Suppose Jeffrey decides to bake chocolate muffins. Which result would be a cost?

 - Jeffrey will give up some muffins. He could have made more pumpkin muffins than chocolate muffins.
 - Jeffrey will get to eat chocolate muffins. He thinks chocolate muffins are tastier than pumpkin muffins.
This result is a cost. It involves giving up or spending something that Jeffrey wants or needs:
Jeffrey will give up some muffins. He could have made more pumpkin muffins than chocolate muffins.