Final answer:
When a warm metal bar is placed into ice water, both the bar and the water are endothermic, meaning that they both absorb heat from the surroundings and experience a decrease in temperature.
Step-by-step explanation:
The correct statement that describes what occurs at the molecular level when a warm metal bar is placed into ice water is option D: Both the bar and the water are endothermic. When the warm metal bar is placed into ice water, heat is transferred from the metal bar to the water, causing the metal bar to cool down and the water to warm up. This transfer of heat is an endothermic process because heat is being absorbed from the surroundings. Both the bar and the water experience a decrease in temperature as a result of the energy transfer.