Final answer:
The auditor needs to clearly express an opinion based on audit evidence obtained in a written report according to GAAS Principle 7.
Step-by-step explanation:
The correct answer is d. Principle 7.
According to the AICPA (American Institute of Certified Public Accountants), Principle 7 of Generally Accepted Auditing Standards (GAAS) states that the auditor needs to clearly express an opinion based on audit evidence obtained in the form of a written report. This principle emphasizes the importance of providing an explicit conclusion or opinion on the financial statements of an entity after conducting an audit.
For example, if an auditor has gathered sufficient and appropriate evidence through procedures such as inspection, observation, inquiries, and analytical procedures, they will need to express their opinion through a written report that is based on their audit findings.