Two identical steel spheres are placed in an insulated container so they can exchange energy only with each other. Sphere A is initially at 80∘C and sphere B at 20∘C. Which statement most accurately describes the subsequent thermal energy transfer?
a) Thermal energy flows from sphere B to sphere A until they both reach 50∘C.
b) No thermal energy is exchanged because the spheres are inside an insulated container.
c) Thermal energy flows from sphere A to sphere B until the two spheres reach thermal equilibrium at 50∘C.
d) Thermal energy is exchanged equally in both directions so each sphere remains at its original temperature.