What is an easy way for a responsible user to get real-time updates on the signals for a particular KPI?

An easy way for a responsible user to get real-time updates on the signals for a particular KPI is to receive email notifications. When a signal is detected on a KPI for which they are responsible, or when other signal-related events occur, responsible users can receive automatic email notifications. This ensures they are promptly informed about significant changes or updates related to their KPIs without the need to continuously monitor dashboards or manually check for signals. Therefore, the correct answer is B. Receive email notifications.