I believe the answer is: scarcity and opportunity costs
A concert tend to happen on unpredicatble time, which make it considered to be scarce among fans. When we are forced to choose between going to concert or study, we would be forced to weigh the opportunity cost that arise when we sacrifice a certain option to pursue another, and choose the activity that give us the most benefit.
<span>e. be ethical
She is being ethical by paying attention to others through being respectful. It is important to treat others how you want to be treated. Taking other's opinions into consideration is one way to do this.</span>
