Final answer:
During glacial retreat, the position of the glacier's toe terminus moves back towards the origin of the glacier.
Step-by-step explanation:
During glacial retreat, the position of the glacier's toe terminus moves back toward the origin of the glacier, even though ice continues to flow toward the toe. This is the correct answer, option b. Glacial retreat occurs when the rate of ablation (melting and evaporation) exceeds the rate of accumulation (snowfall). As a result, the glacier begins to shrink and the ice mass moves back towards the source area.