In [this key].
Minimalist Terry Riley wrote an improvisational work titled after its 53 phrases In [this key]. This key of both the Jupiter Symphony and the "Jupiter" movement of The Planets is the relative major of (*) A minor. Instruments pitched in this key include the double bass, tuba, and others pitched at "concert pitch". This major key's scale can be played on a piano without using a black key. For 10 points, name this common musical key with no sharps or flats.
Minimalist Terry Riley wrote an improvisational work titled after its 53 phrases
C Major (prompt on "C" before "relative major;" accept C after that point)