Similar to the Campeonato Brasileiro, groups from the lessen series, which include B and C, can be promoted to the top division each year. In the case of Italy, only the leading three teams in Serie B are promoted to Serie A (in Brazil, promotion happens for 4 groups in https://josuefztmf.ltfblog.com/36343708/not-known-facts-about-what-is-serie-a