What Does Refractory Mean in Terms of Periodontal Disease States

What does refractory mean in terms of periodontal disease states?

A) Aggressive periodontal disease that does not respond to recommended therapy
B) Chronic periodontal disease that responds to antimicrobial therapy in addition to mechanical therapy
C) Periodontal disease that continues to progress despite client compliance with recommended oral self-care and professional care
D) Bone or attachment loss that is ongoing at the time of the examination