What is the relationship between changes in opportunity costs and changes in behavior?
The relationship between these two variables is an inverse relationship. That is, as one goes up, the other goes down. As the opportunity cost of a given behavior changes, the frequency of that behavior changes in the opposite direction.
Opportunity cost is what I give up in order to do a certain action. If the opportunity cost goes up, I have to give up more to do that action and I will become less likely to do it. If the opportunity cost goes down, I will be more likely to do that action. Thus, the relationship is inverse.