burrowing below the frost point of the soil surface burrowing in tree trunks above the soil surface consuming roots found under the soil surface consuming organisms found in the soil surface
I gave my students this multiple choice question: A population of ground squirrels has established a community in the grasslands of the Great Plains. Temperatures often reach -15°C for most of the winter. What is the most likely behavior the ground squirrels use to survive these winter temperatures?

Only one answer is correct among these 4 choices:
- burrowing below the frost point of the soil surface
- burrowing in tree trunks above the soil surface
- consuming roots found under the soil surface
- consuming organisms found in the soil surface

Could you tell me which one is correct?

burrowing below the frost point of the soil surface