You are presented with the question "what do some touch receptors sense differences in?" and the following answer choices: 
- voltage
 - visible energy
 - fingers
 - refraction of light
 - gravity shifts
 - amount of heat
 - the skin
 - change in density

Now knowing that some touch receptors sense differences in temperature or pain and temperature Temperature is an measurement of the amount of heat, choose the best answer.


 

      amount of heat   