Final answer:
The element used to represent friendship in Anne Frank's 'The Diary of a Young Girl' is 'Theme,' which is an abstract concept explored through characters, motifs, and symbols.
Step-by-step explanation:
In The Diary of a Young Girl by Anne Frank, the story element used to represent friendship is theme. A theme is an underlying message or central idea that recurs throughout a literary work and provides insight into the text’s deeper meanings. In this context, the friendship that develops among the characters in hiding, particularly those relationships that Anne details in her diary, serves as a poignant theme demonstrating human connection in the face of adversity. Themes are abstract concepts, and they are explored through various literary techniques including but not limited to characters and their interactions, symbols, and motifs. Recurring motifs and symbols in a story, such as shared experiences or personal mementos in Anne's diary, can point to the theme of friendship by emphasizing its importance and prevalence in the narrative.