The correct option is C one-digit
Detailed step-by-step solution:
When we subtract a number from 10, we always get a one-digit number.
For example: 10 – 6 = 4
10 – 7 = 3
10 – 5 = 5, etc.
In all such cases we always get a difference which is a one-digit number.
Hence, Option C is correct.