B

The 2019 EULAR/ACR classification criteria for systemic lupus erythematosus make a positive antinuclear antibody (ANA) test ≥1:80 an obligatory entry criterion—without it, SLE cannot be classified or diagnosed, whereas drug-induced lupus, Sjögren syndrome, and scleroderma each have accepted diagnostic pathways that may be ANA-negative in a minority of cases [Aringer et al., 2019, PMID 31385462].