You are presented with the question "Male dogs use_  in urine to mark their territory." and the following answer choices: 
- ammonia
 - Chemical energy
 - proteins
 - semiochemicals
 - animals
 - heat produced
 - nitric oxide
 - They have thick fur

Now knowing that male dogs use pheromones in urine to mark their territory and pheromones are a sub-category of semiochemicals, choose the best answer.


 

    semiochemicals     