The correct response regarding Kendra's opportunity cost if she chooses to go to Abby's house is:
The net value to Kendra of going to Samuel's house to play games.
Opportunity cost refers to the value of the next best alternative that is forgone when making a decision. In this case, if Kendra decides to go to Abby's house, the opportunity cost would be the value or enjoyment she would have received from going to Samuel's house to play board games.