Which of the following is true of RAIM?

The statement that RAIM verifies the integrity of the GPS signal is accurate. RAIM, or Receiver Autonomous Integrity Monitoring, is a crucial feature in GPS systems that helps ensure the reliability of the position data being used by a pilot or for navigation purposes. It works by assessing the measurements from multiple GPS satellites to detect any anomalies or faults that could affect the accuracy and safety of the provided location information.

RAIM utilizes a minimum of five satellites to function effectively, enabling it to determine if the GPS information received is trustworthy. If one of the satellites is providing incorrect data, RAIM can alert the user to the integrity issue, allowing for the continued safe operation of navigation tasks. This function is essential for maintaining safety, particularly in aviation contexts where precision is critical.

In comparison, the other options do not accurately describe RAIM's capabilities or requirements. RAIM does not inherently improve the accuracy of GPS signals, nor does it require only four satellites to operate effectively. Additionally, RAIM does not enhance the user segment satellites; rather, it monitors the data received from existing satellites to ensure its integrity.