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 "Male dogs use_  in urine to mark their territory." with the following options: 
- ammonia
 - Chemical energy
 - proteins
 - semiochemicals
 - animals
 - heat produced
 - nitric oxide
 - They have thick fur


 

    semiochemicals     