What phenomenon is primarily due to post-glacial isostatic rebound?

Post-glacial isostatic rebound refers to the gradual rising of land that was previously compressed under the weight of ice sheets during past glacial periods. As the ice melts, the land begins to recover and elevate due to the decrease in pressure. This phenomenon is particularly pronounced in areas that were heavily glaciated, such as Scandinavia and parts of Canada.

In this context, the coastline of the Gulf of Bothnia gradually receding over the past millennia is a direct result of post-glacial isostatic rebound. As the land in this region rises due to the melting of glaciers and subsequent uplift, it is associated with changes in sea level relative to the land, which can cause perceived recession of coastlines in certain areas. Therefore, the process of isostatic rebound is closely linked to the observed geological changes in the region, making this choice correct.

The other options described do not directly tie into post-glacial isostatic rebound. For instance, while the sinking of Venice is a significant geological phenomenon, it is primarily due to sediment compaction and human activity rather than isostatic rebound. The cooling of the Gulf Stream is related to oceanic and atmospheric change, not land elevation changes. Similarly, iceberg calving, while associated