A) Correct answer (B): RAS is immune-mediated inflammatory condition where immune system mistakenly attacks oral mucosal cells; not viral or bacterial infection and cannot be transmitted person-to-person | B) Other options incorrect: (A) location of involvement does not determine infectiousness, (C) steroid response indicates immune mechanism not proof of non-infection, (D) RAS affects adults and children, (E) absence of fever does not necessarily rule out infection | C) Immunology or oral disease specialist consultation required when: severe recurrent episodes (>6 times/year), large ulcers impeding nutrition, or suspected associated systemic disease (Behçet, Crohn's) | D) Presence of fever and systemic symptoms with ulcers changes answer and directs toward Behçet disease or secondary viral infection | E) Consultant Pearl: RAS is non-infectious autoimmune disease; triggering factors: trauma, stress, vitamin deficiency, food sensitivities | F) Sources: Clin Rev Allergy Immunol 2021 — RAS Immunopathogenesis | Oral Dis 2020 — Non-infectious Oral Ulcers | J Oral Pathol Med 2019 — Aphthous Stomatitis Etiology