Final answer:
When ice melts into water, a change in state (solid to liquid) and position of the molecules occurs. However, the substance's composition remains the same (H2O).
Step-by-step explanation:
When ice melts to form water, the change that occurs is a change in state. This change is called a phase change, specifically from a solid to a liquid state. The composition of the substance does not change, meaning the ice and the water are both H2O. The position of the molecules does change, however, as the molecules in a liquid have more freedom to move than those in a solid. Therefore, the most accurate answer would be a combination of a and c: state and position.
Learn more about State Change