Explanation:

Correct option 4: impartiality

let's analyze each option:

1. dishonesty

This is the opposite of probity.

2. parley

Means a conference or discussion, especially between enemies. Not related to probity.

3. simplicity

Not the same. Simplicity means being simple or uncomplicated, not necessarily honest or principled.

4. impartiality

Closely related, though not identical. It means being unbiased or fair, which aligns with moral uprightness. Among the options, this is the closest substitute for probity, though not a perfect synonym.

Final Answer: 4. impartiality