Red and Green,CPAs Are the External Auditors for Blue Corporation,a

Red and Green,CPAs are the external auditors for Blue Corporation,a publicly-held company.Blue Corporation has outsourced its internal audit function to Red and Green.Which of the following statements is true?

A) Doing internal audit work does not impair the independence of Red and Green.
B) The independence of Red and Green is impaired only if employees of Red and Green act in a management capacity or make management decisions.
C) The independence of Red and Green is impaired only if a member of Red and Green's engagement team is hired to manage an accounting function in Blue Corporation.
D) Public accounting firms cannot be both the internal and external auditors for publicly-held companies and maintain independence.