How did the ocean's oxygenation relate to the breakup of Kenorland?

The ocean's oxygenation during the time of the breakup of Kenorland is significant because it marks a critical period in Earth's history known as the Great Oxidation Event (GOE). This event was characterized by a substantial increase in atmospheric oxygen produced by photosynthetic organisms. The breakup of Kenorland, which occurred during the late Neoproterozoic era, coincided with this period of increasing oxygen levels in the oceans.

As Kenorland began to break apart, geological processes, including the exposure of new landmasses and changes in ocean circulation, likely facilitated the proliferation of microbial life, particularly cyanobacteria, which were responsible for oxygen production. The timing of ocean oxygenation during this tectonic activity suggests that the breakup allowed for more diverse ecosystems to develop and flourish in the oceans, contributing to the rise of oxygen levels.

Thus, the correct choice emphasizes that ocean oxygenation was starting to occur at the time of the breakup, as the geological and biological changes occurring then were interlinked, enhancing the conditions that would lead to increased oxygen in the ocean and atmosphere, fundamentally altering life on Earth.