Explanation:

- Self-Control: This generally refers to an individual's ability to regulate their emotions and actions. It doesn't capture the necessity for an external perspective in auditing.

- Objective: Being objective means not allowing personal feelings or biases to affect judgment. It is important but doesn't fully describe freedom from influence.

- Independence: Independence in auditing means being free from influences that could affect the auditor's impartiality and objectivity. It ensures that the auditor can give an honest, unbiased opinion.

- Unbiased: This implies an absence of preconceived notions and fair judgment. While relevant, it doesn’t encompass all the aspects of auditor freedom from influence.