SBAS improves the performance (position accuracy) of GNSS/GPS receivers by?

The correct answer acknowledges that Satellite-Based Augmentation Systems (SBAS) enhance the performance and accuracy of Global Navigation Satellite System (GNSS) or GPS receivers by introducing additional signals originating from geostationary satellites. This is significant because these additional signals contain corrections and enhancements to the basic GPS signal, effectively improving the positional accuracy that GPS receivers can achieve.

Geostationary satellites are positioned in such a way that they maintain a constant position relative to a specific point on the Earth's surface, making them ideal for broadcasting correction data over wide areas. By utilizing this extra information, SBAS can effectively minimize errors that arise from various factors such as atmospheric conditions and satellite clock inaccuracies, thus resulting in higher precision navigation.

This method contrasts with the other options, which either misrepresent the nature of the signals used (such as suggesting they come from navigation satellites rather than geostationary ones) or imply a focus solely on reducing clock errors without highlighting the overall augmentation to the GPS signal itself. This further emphasizes the importance of the role that additional geostationary signals play in improving GNSS receiver performance.