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

Fact 2: Pheromones are natural aphrodisiacs.

Given the two facts above, answer the question "What do male dogs use in urine to mark their territory?" with the following options: 
- Natural aphrodisiacs
 - competing for resources
 - Tails
 - Urine  cleaner
 - Something coming from a gland
 - Chemical energy
 - an area swollen with pus
 - Chew toys


 

 Natural aphrodisiacs        