In the Chinese Wall model, suppose the Bank COI Class contains Bank of America, Citibank, and Bank of the West; the Gasoline Company COI Class contains Shell Oil, Standard Oil, and Exxon. Suppose initially user Alice can read all the companies data. After Alice reads Shell Oils data, which companies data can Alice still read? If a system only stores the basic access control matrix, can the system enforce the Chinese Wall model and why?