Male dogs use pheromones in urine to mark their territory, and pheromones are a sub-category of semiochemicals. Given these facts, male dogs use_  in urine to mark their territory. among the following options:
- ammonia
 - Chemical energy
 - proteins
 - semiochemicals
 - animals
 - heat produced
 - nitric oxide
 - They have thick fur


 

    semiochemicals     