Apropos can be played by many combinations of Violin, Viola, Cello, for 2-4 players.

Violin and Viola

Violin and Cello

Viola and Cello

2 Violins

2 Violas

2 Cellos

Violin, Viola, Cello

2 Violins and Viola

Violin and 2 Violas

2 Violins and Cello

2 Violas and Cello

3 Violins

3 Violas

3 Cellos

2 Violins, Viola, and Cello

4 Violins

4 Violas

Viola and 3 Cellos

4 Cellos

Other combinations are possible with the right clef-reading.