Final answer:
The correct statement regarding an auditor's opinion on the effectiveness of internal control is that the auditor assesses internal controls as of the end of the fiscal year.
Step-by-step explanation:
Among the statements provided about auditor's opinion on the effectiveness of internal control, the first one is true: The auditor is attesting to the effectiveness of internal controls as of the end of the fiscal year. This means the auditor's assessment is based on the status of the internal controls at a specific point in time, namely the fiscal year-end. If the client remedies a material weakness before the end of the fiscal year, the auditor may not necessarily have to issue a qualified opinion or disclaimer of opinion; rather, it depends on whether the control is operating effectively at the year-end.
A scope limitation could lead to a qualified opinion, a disclaimer of opinion, or even an adverse opinion depending on the circumstances and the auditor's ability to obtain sufficient appropriate audit evidence. Lastly, Section 404 of the Sarbanes-Oxley Act does require auditors to evaluate the effectiveness of internal control over financial reporting, but it does not expect auditors to design their audits to detect all deficiencies in internal control, as some deficiencies may be immaterial.