Nitrogen Balance Testing Is Planned for a Newly Admitted Client

Nitrogen balance testing is planned for a newly admitted client. What instruction to the staff caring for this client is essential?

A) Accurate measurement of protein intake is very important.
B) Remove the client's oxygen cannula 10 minutes prior to the test.
C) All urine output should be collected for 48 hours.
D) Keep the client NPO beginning at midnight before the test.