In office lighting design for reading printed documents, what is the recommended minimum luminance contrast…

In office lighting design for reading printed documents, what is the recommended minimum luminance contrast…: a task in TaskCompendium spike examples (Harbor dataset). A: 1:1 B: 2:1 C: 3:1 D: 4:1 E: 5:1 F: 7:1 G: 10:1 H: 15:1 I: 20:1 J: No specific ratio is recommended