Final answer:
The fair value option for valuation of marketable securities will affect the Valuation and allocation assertion the most.
Step-by-step explanation:
When a company decides to use the fair value option for valuation of marketable securities, it is most likely to affect the Valuation and allocation assertion the most.
This is because the fair value option allows companies to report the market value of their securities on their financial statements, which can result in fluctuations in the reported value of the securities.
The fair value option can impact the valuation of the company's assets and how they are allocated in the financial statements.