Six keys. Also there's these guidelines for the evaluation:
"The material presented should demonstrate a clear and nuanced understanding of the 6 scales. That the scales were played correctly with rhythmic variation, and fluidity was demonstrated as well."
"The melodic, harmonic, and/or rhythmic material presented in the audio was accurate and fitting and represented the correct tonality of the 6 scales."

I just read this on The Bullet-proof musician site that makes sense: "Art and fear. Specifically, that if we want to be taken seriously as an artist, we must look at the score with our own eyes and our own ears and take a stand. Rather than copying others’ ideas or waiting for others to endorse or support our ideas, we must make our own conclusions about what we see in the music and bring our ideas to life boldly, courageously, and without question or apology.

That even if we don’t know what is “right” or “wrong”, we simply must make some decision and commit to it until we come up with a better idea. That abstaining from making a decision is not an option. Nor is delaying our inquiry into the bigger questions while we obsess about intonation and hide behind technique."
http://www.bulletproofmusician.com/the-most-valuable-lesson-i-learned-from-isaac-stern/