The two ways that one could interpret this, Many2Many and One2Many both imply min=0 and max=(inf.)

😎

R2 => Many to many, min=0,max=(inf)

+-----------+ +----+ +------+

| A(a)+B(b) |-0---0<| R2 |>0---+-| C... |

+-----------+ +----+ +------+

R2 => One to many, min=0,max=(inf)

+-----------+ +------+

| A(a)+B(b) |>0---+-| C... |

+-----------+ +------+