Final answer:
Expansion Realty must keep records of sales to foreigners for at least 5 years as required by the IRS and FIRPTA.
Step-by-step explanation:
The question relates to the length of time that Expansion Realty, a real estate company dealing with foreign investment properties in California, is required by law to keep records of their sales transactions. According to the Internal Revenue Service (IRS) guidelines and the Foreign Investment in Real Property Tax Act (FIRPTA), real estate companies in the United States are required to keep records of all their transactions for a minimum of 5 years after the tax return is filed. This period is to ensure that all the details pertaining to the transactions can be reviewed in case of an audit or other legal requirements.