In the article below I need to identify two economic principles or concepts and explain how they relate to both articles.

Article 1:

I have listed Opportunity Costs and Economic Incentives. Do they apply? If not which concepts should I look into and why?

Supplementary private health insurance: The impact of physician financial incentives on medical practice. Journal of Health Economics. Published. https://doi.org/10.1002/hec.4443

Article 2:

I have listed Shortage and Framing Effects, I am completely unsure if either of these are actual concepts or principles. Are they or are they not? If not which concept or principle should I be speaking on in reference to the article listed below?

Li, X., & Waibel, C. (2021). Patients' free choice of physicians is not always good. Health Economics. Published. https://doi.org/10.1002/hec.4407