4. You are testing a PIN validator, which accepts valid PINs and rejects invalid PINs. A PIN is a sequence of digits. A PIN is valid if it consists of four digits, at least two of which are different. You have identified the following valid equivalence partitions:
Variable: PIN code length
- The partition “length correct” - four-digit PINs
- The partition “length incorrect” - PINs with length other than 4
Variable: Number of different digits
- The partition “number of different digits correct” - PINs with at least two different digits
- The partition “number of different digits incorrect” - PINs with all digits being the same
Which of the following is a MINIMUM set of input test data that covers all identified equivalence partitions?