D major piano scale. From the Root note D, we create the D piano major chord. Then from the Root note using the piano formula for major scales- RWWHWWWH (R for root note, W for whole step and H fro half step), we create our D major scale.
From the above diagram, piano notes D, F3 and A which when struck together creates the D major piano chord. Then applying the piano major scales formula, we get the following notes depicted in the below diagram: D,E, F#, G, A,B, C#, and D again. This is what is termed as D piano major scale.