请问sales day book中的漏记或错误会影响receivable ledger control account，那会不会影响receivable ledger account呢？

根据书上的图表，应该是不影响rla的，但是这样的话下面这题目就有问题了：

the following figures were extracted from the records of Duncan Co as at 30 June 2008

Receivables ledger control account   20,770

total per listing of receivables ledger balances    20,320

which of the following errors could have led to this discrepancy?

a  a credit note for 450 was omitted form the sales day book

b  the receivables ledger column in the cash receipts book which totalled 4830 was posted to the receivable ledger control account as 4380

c an invoice for 270 was entered in the sales day book as 720

答案是b

解释是a，c会同时影响rla和rlca

哪位高手能帮我解决一下啊，谢谢

应该是B，应为，ac确实过账会两个账户是过相同的数字，所以不会不一样，而B是只有一个账户出错，rlca少记了

只有b是只在过一个账户时候错了，而ac都是同时过入2个账户，所以，ac不会不平衡