Final answer:
Starting flossing more is an example of an ill-defined problem.
Step-by-step explanation:
An ill-defined problem refers to a problem that lacks a clear statement or goal, making it difficult to determine when it has been solved. Out of the options given, starting flossing more is an example of an ill-defined problem. This is because it doesn't specify how often or how much flossing needs to be done to achieve the goal.