The nurse receives a new prescription to administer oxygen at 3 L/minute via a nasal cannula to maintain an oxygen saturation between 90 and 100% for an adult client. The nurse obtains an oxygen saturation reading of 85% and, after repositioning the oximeter on a different finger, obtains a second reading of 87%. Which action should the nurse take next?

D Place the pulse oximeter on the client's earlobe. A Place the client in a Trendelenburg position. B Document the second reading in the client record. C Securely place the prongs of the cannula in the nostrils.