B. What did Millie do in the park with her brother? 1) She played football. 2) She read books. 3) She played badminton.

Let's find the information in the text. The text says, "Millie and Fred played badminton, then Millie read a book and Fred played football with other boys." It explicitly mentions that Millie and Fred (her brother) played badminton in the park. The correct answer is **3) She played badminton**.