Fact 1: Male dogs use pheromones in urine to mark their territory.

Fact 2: Pheromones are a sub-category of semiochemicals.

Given the two facts above, answer the question "What do dogs use to mark their territory?" with the following options: 
- water
 - Chemicals
 - layers of fat
 - food
 - Animal fur
 - heat energy
 - Scratches
 - heat produced


 

  Chemicals       