The correct procedure for testing for ketones using a reagent strip includes ____. 

A. using a strip you found sitting out on the counter
B. using a strip from a bottle that was opened 7 months ago
C. testing urine immediately or covering and refrigerating it until you can test it
D. testing a urine sample immediately after removing it from the refrigerator
E. running a control sample once a year to check for proper operation

C. testing urine immediately or covering and refrigerating it until you can test it
Test urine immediately. If this is not possible, cover and refrigerate it until you can test it. Allow the sample to come back to room temperature before testing.