You are presented with the question "Male dogs use what in their urine to mark their territory?" and the following answer choices: 
- hydrocarbons
 - volatile substances
 - kinetic energy
 - an area swollen with pus
 - Chemical energy
 - competing for resources
 - add a solute
 - Positive charges

Now knowing that male dogs use pheromones in urine to mark their territory and generally, pheromones are volatile substances, choose the best answer.


 

  volatile substances       