Question：The debit side of a trial balance totals $50 more than the credit side.
　　Which one of the following could this be due to?
　　A. a purchase of goods for $50 being omitted from the payables control account
　　B. a sale of goods for $50 being omitted from the receivables control account
　　C. an invoice of $25 for electricity being credited to the electricity account
　　D. a receipt for $50 from a customer being omitted from the cash book
　　The correct answer is: a purchase of goods for $50 being omitted from the payables control account.
　　解析：'A sale of goods for $50 being omitted from the receivables control account' and 'an invoice of $25 for electricity being credited to the electricity account' would make the credit side $50 higher.
　　'A receipt for $50 from a customer being omitted from the cash book' would have no effect.