Final answer:
RUM can work on an unmonitored host through JavaScript injection, which involves inserting code into a webpage to collect performance data.
Step-by-step explanation:
RUM (Real User Monitoring) can work on an unmonitored host through JavaScript injection. JavaScript injection involves inserting a piece of code into a webpage that collects and sends performance data back to the monitoring system. This allows RUM to capture and analyze user interactions and monitor the performance of the host.
For example, a website owner can include a JavaScript snippet on their webpage that measures the time it takes for different elements to load, the number of server requests made, and other performance metrics. This data is then sent to a monitoring system which provides insights into the user experience and identifies areas for optimization.
Therefore, the correct answer is c) Through JavaScript injection.