Which of the Following Describes a Control Weakness

Which of the following describes a control weakness?

A) Purchasing procedures are well designed and are followed unless otherwise directed by the purchasing supervisor.
B) Pre-numbered blank purchase orders are secured within the purchasing department.
C) Normal operational purchases fall in the range from $500 to $1, 000 with two signatures required for purchases over $1, 000.
D) The purchasing agent invests in a publicly traded mutual fund that lists the stock of one of the company's suppliers in its portfolio.