About Familiar Archetype Sage and Sage’s Knowledge?

Sage’s Knowledge (Ex)

A sage stores information on every topic and is happy to lecture its master on the finer points. A sage can attempt all Knowledge checks untrained and receives a bonus on all Knowledge checks equal to 1/2 its level. Additionally, a sage gains 2 skill ranks at each level.

Does the "2 skill ranks at each level" mean 2 skills ranks to add to a singular skill, all skills, to a class skill, all class skills, a X-class skill, or all x-class skill?