B

HBe Ag appears in the blood when the virus is actively replicating, and its presence correlates with high HBV DNA levels and marked transmissibility, making this the phase of greatest infectivity [Lindenschmidt et al., 1984, PMID 6716909]. HBsAg merely denotes infection, HBcAg is not detectable in serum, and anti-HBs signifies recovery or immunity, none of which indicate peak infectivity.