The nurse is performing a routine assessment of an IV site for a client receiving both IV fluids and medications through the line. The client reports tenderness when the nurse touches the arm above the site. Which finding should the nurse expect which will require immediate intervention?

A. Sluggish blood return suggests a need for assessment but is not immediately critical. B. A red streak tracking the vein indicates phlebitis or infection, requiring immediate intervention to prevent complications such as thrombophlebitis or sepsis. C. Circumferential skin irritation is concerning but not as urgent as a sign of infection. D. A cool sensation might indicate infiltration but is less critical compared to signs of infection or phlebitis.