You are presented with the question "When a cooler object touches a warmer object, conductivity varies with what?" and the following answer choices: 
- heat energy
 - flow of electrons
 - voltage
 - activation energy
 - Electrical energy
 - sediment type
 - energy barrier
 - friction

Now knowing that when a cooler object touches a warmer object , thermal conduction occurs and thermal conductivity varies with sediment type, choose the best answer.


 

      sediment type   