Smith Manufacturing Company’s accounts receivable clerk has a friend who is also a Smith’s customer. The accounts receivable clerk has issued fictitious credit memos to his friend for goods supposedly returned. The most effective procedure for preventing this activity is to:

    a.    prenumber and account for all credit memorandums.
    b.    require receiving reports to support all credit memorandums before they are approved.
    c.    have independent sales and accounts receivable departments.
    d.    mail monthly statements to customers.