Final answer:
The phase that involves qualitative problem definition in the stages of risk assessment is Risk Analysis (C).
Step-by-step explanation:
In the stages of risk assessment, the phase that involves qualitative problem definition is Risk Analysis (C).
Risk analysis involves evaluating and assessing the risks associated with a particular situation. It includes identifying and defining the problem that needs to be addressed.
For example, let's say you are conducting a risk assessment for a chemical plant. In the risk analysis phase, you would identify potential hazards and evaluate their impact on human health and the environment.