When our lives cease to be inward and private, conversation degenerates to become mindless and sterile. This is best represented by option B.
In Henry David Thoreau’s quote, he expresses his thought that conversations tend to become more open when focusing more on external factors and steering away from private thoughts and contemplations. The reason for this is because introspection was seen as essential for genuine conversations between two or more people. As a result of not keeping the inward conversation, the chats lack more and more imagination and interest. Therefore, option B represents this best.