Question

Passage:
For decades, plant physiologists regarded the emission of volatile organic compounds (VOCs) by damaged plants primarily as metabolic byproducts of cellular stress or as direct deterrents against herbivores. However, controlled experiments in the late 1990s revealed that neighboring, undamaged plants exposed to these airborne signals upregulate their own chemical defenses prior to attack. This discovery prompted some researchers to contend that plants actively engage in intentional inter-plant communication.

Yet, this communicative hypothesis drew scrutiny from evolutionary biologists, who argued that natural selection rarely favors altruistic signaling between non-kin individuals when such signals incur metabolic costs without conferring direct fitness benefits to the emitter. Instead, critics proposed an alternative framework: VOC emissions originally evolved as a vascularly constrained self-signaling mechanism. Because internal systemic transport within a single plant can be slow or structurally obstructed, airborne signaling allows distant leaves of the same organism to coordinate defensive responses rapidly. Eavesdropping by neighboring plants is thus best understood as an incidental ecological byproduct rather than an evolutionary adaptation driven by altruism. Recently, integrated ecological models have begun to synthesize these perspectives by examining microclimate variations and genetic relatedness within plant clusters, shifting consensus toward viewing VOC phenomena through the dual lenses of kin selection and self-signaling efficiency.

Which of the following best states the primary purpose of the passage?