Answer: The options that apply are "A. In both situations there may be a lack of interest in controlling costs if those costs are not borne directly by the person making the decision." and "D. The agency problem leads an individual (in your case) and corporate managers (in the corporate setting) to put their own self-interest ahead of the interests of the shareholders (your parents in your case)."
Explanation: The agency theory has 2 parts an Individual (manager) who manages the company but does not own.
And a principal (owners or shareholders) who provide the capital.
The main problem is that there is a conflict of interest between them.