The anatomical landmarks used to help establish the location of the posterior palatal seal of a maxillary complete denture include the

pterygomaxillary notches and the fovea palatinae.

pterygomaxillary notches and the posterior nasal spine

posterior border of the tuberosities and the posterior border of the palatine bone.

anterior border of the tuberosities, the palatine raphe and the posterior border of the palatine bone.