In Formulating the Teaching Plan for a Patient Who Is

In formulating the teaching plan for a patient who is taking the oral hypoglycemic agent metformin (Glucophage) , the nurse should include which priority instruction? "Notify your healthcare provider if

A) you need a diagnostic test that uses iodinated contrast."
B) your urine becomes orange or red-tinted."
C) your urine becomes more concentrated."
D) you need an intermittent or indwelling urinary catheterization."