Final answer:
During glacial retreat, the glacier's terminus moves back toward the origin as the ice continues flowing toward the toe. This retreat occurs because melting exceeds snow accumulation, causing the ice to retract.
Step-by-step explanation:
During a glacial retreat, the position of the glacier's toe (terminus) moves back toward the origin of the glacier. This occurs even though the ice within the glacier continues to flow toward the toe. The correct answer to the question is option b) 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. Essentially, as the glacier melts, the terminus retracts, but the ice itself doesn't flow back up towards the origin; it continues its downward flow until it melts or sublimates.
Glaciers are dynamic systems that respond to changes in temperature and precipitation, retreating when the rate of melting outpaces the rate of snow accumulation. It's important to note that glacial ice is always moving under the force of gravity, but when more ice melts from the terminus than is replenished by snowfall at the accumulation zone, the net effect is a retreat of the glacier's terminus.