Final answer:
Realism is demonstrated in a project selection model through the representation of actual project constraints and conditions.
Step-by-step explanation:
The quality of realism required of a project selection model is best demonstrated by the representation of actual project constraints and conditions. This means that the model should accurately incorporate the limitations, requirements, and factors that exist in real projects.
By considering these real-life factors, the project selection model becomes more reliable and practical in decision-making.