In which form would a theme be presented before being repeated with slight changes?

The artist that refined oil painting with techniques including mixing pigment with linseed oil and using tiny brushes was

a. Jan van Eyck. b. Paolo Uccello. c. Gentile da Fabriano. d. Leonardo da Vinci.

Which stride pianist lifted the art form to a new level of virtuosity, even though he was almost blind?

a. Art Tatum b. James P. Johnson c. Fats Waller d. Nat "King" Cole