Final answer:
The main idea of a text relates to its theme or central conflict, which is derived from understanding the plot and its elements. Without full context, it is not possible to definitively decide the main idea; however, details of the plot offer clues. The setting might also play a significant role in uncovering the main themes of a book.
Step-by-step explanation:
To determine the main idea of an article or text, it's important to have a grasp of the plot and how it unravels. This includes understanding the progression of events from introduction, through rising action, to the climax, and finally to the conclusion. The main idea often relates to the theme or central conflict presented in the story. When analyzing the relationship between setting and main themes or examining the main ideas of an essay, look for specific and concise sentences that encapsulate the text being examined. These sentences usually point towards the main idea.
From the provided information, it wouldn't be proper to determine the main idea without the context of the full text. However, if one were to guess, option B seems to recall a specific detail (the book is revealing its secrets on a hill) which might align closely with a plot detail rather than a thematic statement. To truly understand the main idea, one should consider the overarching narrative and how characters, settings, and events interact within the plot.