Which of the Following Situations Indicates a Potential Material Weakness

Which of the following situations indicates a potential material weakness in internal control over acquisitions and expenditures?

A) Purchase orders are not prepared for services that are acquired directly under authorization of department heads.
B) The person who approves purchases also signs the cheques.
C) Unacceptable goods are not recorded on receiving reports.
D) The person who signs the cheques also stamps "paid" on the vouchers.