What report is due within 90 days after a fiscal year's end and contains audited financial statements?

The Form 10-K Annual Report is the correct answer because it is a comprehensive overview of a company's financial performance, and it must be filed with the Securities and Exchange Commission (SEC) within 90 days after the end of the fiscal year. This report provides detailed audited financial statements, which include the balance sheet, income statement, cash flow statement, and notes to the financial statements. Additionally, the Form 10-K includes information about the company’s operations, risk factors, management’s discussion and analysis (MD&A), and details about the company's governance, which helps provide investors with a clear understanding of the company's financial health and operational results.

The other reports listed have different filing requirements and purposes. The Form 10-Q is a quarterly report that provides a less comprehensive update on financial performance, typically filed 40 days after the end of each fiscal quarter and does not require audited financial statements. The Form 8-K is a Current Report used to announce major events that shareholders should know about, and it is filed as needed rather than on a fixed schedule. The Proxy Statement is related to voting and management meetings and is filed prior to a company’s shareholder meetings, but it does not include the comprehensive audited financial statements found in the Form 10-K.