The Nurse Feels Resistance While Trying to Flush the IV

The nurse feels resistance while trying to flush the IV line with a 5-mL syringe of normal saline solution before administering a medication by IV bolus.Which action does the nurse implement next?

A) Use a 3-mL syringe to flush.
B) Aspirate the IV line for a blood return.
C) Check for causes of resistance.
D) Inject the IV medication slowly.