Alone wolf, who doesn’t have a pack travels the forest. when he reaches a new hill that he hasn’t been on before he spends a large amount of time sniffing the trees and rocks outcrops. finally he turns and heads back from where he came, recognizing this is the territory of another wolf. what’s most likely responsible for communicating this information to the wolf?

a. the tracks of other wolves on the hill

b. pheromones

c. language

d. markings on the trees