When a Male Kangaroo Smells the Urine of a Female

When a male kangaroo smells the urine of a female kangaroo, information is transmitted to the brain by way of receptors in his vomeronasal organ.What is the process?

A) A chemical in the urine that binds to gustatory receptors indicates presence of the female kangaroo.
B) Urea in the urine binds to olfactory receptor neurons, which convey information about the location of the female kangaroo.
C) Sodium ions in the urine bind to receptors on olfactory neurons and reveal the territory of the female kangaroo.
D) Molecules in the urine that bind to receptors high up in the nasal cavity indicate whether the urine contains toxins, which gives information on the general health of the female kangaroo.
E) A pheromone in the urine that binds to chemoreceptors indicates that the urine is from a conspecific female.