Rule reminder
A REFERENCE CHAIN tracks the same entity across multiple sentences. The typical pattern: INTRODUCE with indefinite article or proper name → MAINTAIN with definite article, pronoun, or synonym → VARY with different expressions to avoid monotony. At B2 level, you should be able to draw these chains and choose the most cohesive expression at any point in the chain.
«Tre studiosi hanno proposto una nuova teoria. [A] ___ si basa su dati sperimentali. [B] Gli scienziati l'hanno presentata a un congresso.» Quale soggetto di A mantiene meglio la coesione?