B: Those methods have less likelihood of being misinterpreted.
Explanation:
Making a phone call or having a personal contact is the best way to convey sensitive information because there are some elements in a personal and direct exchange of words that leaves no room for misunderstanding: the tone of voice, body language, eye contact, attention to what is being shared etc. It is a live communication, the best for sensitive issues.
The central idea is the central, unifying element of the story, which ties together all of the other elements of fiction used by the author to tell the story.
