What does a 'pressure hierarchy' refer to in a multi-zone building?

What does a 'pressure hierarchy' refer to in a multi-zone building?

• A. The building's color scheme
• B. The order of door openings
• C. The flow of water in the system
• D. The intended sequence of positive, neutral, and negative pressures between spaces to control infiltration and ensure contaminant control

Answer: (D)