Question

which form of music consisted mainly of syncopated piano? Blues jazz rock ragtime or bebop

Answer 1

Jazz, because when playing jazz music you swing the second beat of each measure. Therefore syncopating it. 

Answer 2

I believe it could be "Ragtime".

"Ragtime music is characterized by syncopated rhythms, mostly composed for piano" - Plato

I hope this helps for anyone who is having trouble.