What should the VSI indicate during level flight under normal circumstances?

During level flight under normal circumstances, the Vertical Speed Indicator (VSI) should indicate zero or a new zero. This means that the aircraft is neither climbing nor descending but maintaining a constant altitude. The VSI is designed to reflect any changes in vertical speed immediately, so when the aircraft is flying straight and level, with no altitude change, the VSI should show zero.

In this context, a reading of zero or a new zero is critical for ensuring that the pilot is aware of the aircraft's performance and can maintain altitude safely. The other options would indicate a change in altitude, either positive climbing or negative descending, which is not the case in level flight. Therefore, the only appropriate indication during this flight condition is a reading of zero on the VSI.