The correct answer is B. They help the reader visualize the characters' actions.
Step-by-step explanation:
In the passage from A Doll's house, two characters (Helmer and Nora) are having a conversation, due to this, the words of each character are preceded by the name of the character who is speaking, but besides the words said by each character this passage includes information in brackets []. In general terms in grammar, brackets [] are used to introduce information that provides details about the information that is not in brackets; in this case, the excerpt includes information such as [following her] or [counting] that specifies the movements characters do while speaking to each other. In this way, the information in brackets provides further details in terms of movement of characters or stage direction, that help the reader understand better and visualize the characters' actions.