The Nurse Needs to Dilate a Patient's Vein Prior to Inserting

The nurse needs to dilate a patient's vein prior to inserting an IV catheter.Which technique should the nurse use to dilate the patient's vein?

A) Elevate the extremity for 5 minutes.
B) Apply an alcohol swab for 60 seconds.
C) Apply a cool compress for 15 minutes.
D) Apply a tourniquet for up to 3 minutes.