In relation to insolvency:

(b) Explain the business activities that are prohibited or restricted once a decision has been taken to commence bankruptcy proceedings. (4 marks)

某单位会计人员在审核一张购买原材料的原始凭证时，发现凭证上单价和金额有涂改痕迹，且材料单价明显高于市场价格，对于该凭证下列说法正确的是（ ）。

A．不真实的原始凭证

B．不准确的原始凭证

C．会计人员有权不予接受，并向单位负责人报告

D．应予退回，并要求按规定更改补充