Which of the following statements is true with regard to the reimbursement of employee business expenses? a. Provided that reimbursements are received by an employee under a plan which requires the employee to substantiate the expenses to his employer, the amounts are excluded from the definition of wages subject to withholding, without regard to whether the employee actually substantiates the expenditures. b. Reimbursements received by an employee under a plan which contains a requirement to return excess amounts, and the employee does so on a timely basis, are excluded from the definition of wages subject to withholding. c. Reimbursements of ordinary and necessary expenses are subject to federal income tax withholding. d. Excess reimbursements of ordinary and necessary expenses are never subject to withholding. e. All of these choices are true statements.