Hi!
The answer would be D. A doctor ordering tests to be done because he is part owner of the lab
Definition & Example
A conflict of interest is a situation which arises when a person is in such a position that he might be inclined to make decisions or take certain actions that may be influenced by self, public or professional interest. For instance, an employer who is deciding between a pool of applicants of which one is her best friend, but be inclined to hire her.
Explanation
A doctor ordering tests to be done is a conflict of interest as he is the owner of the lab, meaning he might ask needless tests to be done for the very reason because diagnostic tests can be costly, and a partial amount of the money generated by the lab will go to him. So for self-interest (monetary gains) he would order tests.
Hope this helps!