Final answer:
Evolutionary processes are least likely to cause a mass extinction compared to catastrophic events like asteroid impacts or volcanic eruptions, which have historically led to major losses of biodiversity.
Step-by-step explanation:
Of the listed causes of mass extinctions, the one that is least likely to be responsible for such an event is the evolutionary process itself. History demonstrates that mass extinctions are typically triggered by catastrophic events such as asteroid impacts, volcanic eruptions, and drastic climate changes. These events have dramatic consequences on a global scale, such as blocking out the sun and causing a drop-in temperature, which in turn can lead to a collapse of the food chain. Except in one instance tied to cyanobacteria and an increase in atmospheric oxygen, evolutionary processes, such as natural selection or adaptive radiation, do not directly cause mass extinctions but may follow in their aftermath, leading to the development of new species as environments change.