What is the largest contributor to the mass extinction 251 MYA? volcanic activity in the Siberian traps slasiation from the movement of Gondwand the burning of fossi fuels at the equitor (1) asteroid impact

## Step 1<br />The question is asking for the primary cause of the mass extinction that occurred approximately 25 million years ago (MYA). The options provided are volcanic activity in the Siberian Traps, the movement of Gondwana, the burning of fossil fuels at the equator, and an asteroid impact.<br /><br />## Step 2<br />The mass extinction event that occurred around 25 MYA is known as the Cretaceous-Paleogene (K-T or K-Pg) extinction event. This event is most famously associated with the impact of a large asteroid, which is believed to have caused the extinction of the dinosaurs.<br /><br />## Step 3<br />The other options, such as volcanic activity in the Siberian Traps, the movement of Gondwana, and the burning of fossil fuels at the equator, are not the primary causes of the mass extinction event in question.