Final answer:
Pheromones are species-specific chemical signals that prompt behavioral or physiological reactions within that species, unlike general odorants that may be detected by many species but do not elicit specific intraspecific responses.
Step-by-step explanation:
From the perspective of the recipient of the signal, pheromones differ from other odorants in that they are chemical signals specifically recognized and used for communication within the same species. Unlike general odorants that can be detected and recognized by any organism with the appropriate sensory receptors, pheromones elicit particular behavioral or physiological responses, typically among members of the same species. These chemicals play a vital role in various behaviors such as mate attraction, alarm signaling, territorial marking, and other social cues. For instance, some pheromones are involved in reproductive synchronization, like the case with humans where axillary steroids were linked to women's menstrual cycle synchronization.
Pheromones are not exclusive to any one species and are not related to the particular odor profile of a chemical. They function quite differently from common smells in that they are typically processed by specialized sensory cells and may trigger different brain regions than those activated by ordinary odors. Hence, the correct answer to how pheromones differ from other odorants is: a) Pheromones have a specific odor profile recognizable to a particular species.