Which of the Following Statements Regarding Valuations Used in Accounting

Which of the following statements regarding valuations used in accounting is not correct?

A) Under GAAP, a company must choose to use historical cost accounting for all assets and liabilities.
B) Under IFRS rules, a company's financial statements will typically contain a variety of assets and liabilities using different valuation methods.
C) Even if a company's financial statements contain items valued with different information methods, financial statement readers can still find this information helpful.
D) Even if a company's financial statements contain items valued with different information methods, the financial information may still be useful for deciding on compliance with contracts, such as bonus agreements.