Wizard, i think you are referring to Non Normal C/L use. As of Normal C/L, neither answer is correct. PM (or PNF) AND PF can respond, depending on the area of reponsability or the specific C/L.
Extract from B737 QRH, Normal C/L Operation chapter:
"The following table shows which pilot calls for the checklist and which pilot reads the checklist. Both pilots visually verify that each item is in the needed configuration or that the step is done. The far right column shows which pilot gives the response."
Hope this helps.