Question ATPL - Airline Transport Pilot license - Radio Navigation

In the event of the re-use of Selective Availability, how does this affect, if at all, the navigation accuracy of the NAVSTAR/GPS satellite navigation system ? - ATPL

It has no influence because, by selecting of the most suitable signals, the computing process in the receiver is quicker

It increases because only signals from satellites in the most suitable geometric constellation are selected by the receiver

It degrades accuracy by reducing the number of available satellites

6 orbital planes with 4 satellites in each plane