Answer the following question: You are presented with the quiz "What uses chemicals in urine to mark their territory?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "male dogs use pheromones in urine to mark their territory" and "pheromones are chemicals produced by insects to communicate". So, what's the best answer to the question?

Select from the following.
(1). rabbit
(2). bears
(3). viruses
(4). male dogs
(5). alpacas
(6). athletes
(7). humans
(8). bacteria
Answer:
(4).