Pheromones are defined as which of the following?

Pheromones are chemical substances produced and released into the environment by animals, which affect the behavior or physiology of others of the same species. They are specifically designed to convey information between individuals, often relating to mating, territory, or alarm signals.

Choosing the option that describes pheromones as odors released by an animal is accurate because it emphasizes the chemical nature of these signals, which are typically detected by the vomeronasal organ in many animals. This distinguishes them from other forms of communication, such as visual or auditory signals, which do not involve chemical dissemination.

In contrast, hormones released during stress refer to internal biochemical messengers involved within an organism and do not function in communication between individuals. Visual signals used for mating involve sight rather than chemical cues. Sounds made by animals to communicate are part of auditory communication, which is also distinct from the chemical communication that pheromones represent. Thus, recognizing pheromones as odors emphasizes their role as chemical communicators in the animal kingdom.