Which GPS protocol is used?

It is mentioned in LEA-6H module datasheet that all listed protocols (NMEA, UBX and RTCM) are available on UART, USB and DDC of 3DR uBlox GPS.
Which means Pixhawk receives all 3 protocols serially via UART on GPS port? If that is correct, which protocol it filters out to use for navigation?

if GPS is capable of UBX, Ardupilot will request that mode, and switch to it.
Compared to NMEA , it’s better, easier to process, and binary (less CPU load).