bigCO averages 500 million per year in annual revenues. Smallco average $10 million per year in average revenues. Which if the following is true about the allowable accounting methods for the firms for tax purposes? a. Both companies can chose either the cash method or the accrual method b. Both companies must use the accrual method c. Bigco must use the accrual method, smallco can choose either. The accrua method or cash methid d. Both companies must use the cash method