Read the following passage and answer the items that follow. Your answers to these items should be based on the passage only.
Invasions of exotic species into new geographic areas sometimes occur naturally and without human agency. However, human actions have increased this trickle to a flood. Human caused introductions may occur either accidentally as a consequence of human transport, or intentionally but illegally to serve some private purpose or legitimately to procure some hoped-for public benefit by bringing a pest under control, producing new agricultural products new agricultural products or providing novel recreational opportunities. Many introduced species are assimilated into communities without much obvious effect. However, some have been responsible for dramatic changes to native species and natural communities. For example, the accidental introduction of the brown tree snake Boigairregularis into Guam, an island in the Pacific, has through nest predation reduced 10 endemic forest bird species to the point of extinction.
One of the major reasons for the world’s great biodiversity is the occurrence of centers of endemism so that similar habitats in different parts of the world are occupied by different groups of species that happen to have evolved there. If every species naturally had access to everywhere on the globe, we might expect a relatively small number of successful species to become dominant in each biome. The extent to which this homogenization can happen naturally is restricted by the limited powers of dispersal. By virtue of the transport opportunities offered by humans, these barriers have been breached by an ever-increasing number of exotic species. The effects of introductions have been to convert a hugely diverse range of local community compositions into something much more homogeneous. It would be wrong, however, to conclude that introducing species to a region will inevitably cause a decline in species richness there. For example, there are numerous species of plants, invertebrates and vertebrates found in continental Europe but absent from the British Isles (many because they have so far failed to recolonize after the last glaciations). Their introduction would be likely to significant detrimental effect noted above arises where aggressive species provide a novel challenge to endemic biotas ill-equipped to deal with them.
Why does man introduce exotic species into new geographical areas?
The correct option is None of the statements (a), (b) and (c) is correct in this context.
The passage explicitly identifies the reasons for human-caused introductions of exotic species into new geographical areas. According to the passage, human-caused introductions may occur in the following ways:
The passage thus presents a tripartite framework of reasons — accidental, intentional-illegal, and intentional-legitimate — for human-mediated introductions. Since the question states that the correct answer is that none of the individual statements (a), (b), and (c) is correct in this context, it follows that each of those options presented only a partial or inaccurate representation of the passage's explanation, failing to capture the complete and precise reasoning as stated therein.
The passage does not attribute exotic species introduction solely to any single motive. Any option that isolates only one reason — whether accidental transport, private interest, or public benefit — as the explanation for why humans introduce exotic species would be incomplete and therefore incorrect as a standalone answer based strictly on the passage.
Key Takeaway: According to the passage, human introduction of exotic species occurs through three distinct pathways — accidental (via transport), intentional-illegal (private purpose), and intentional-legal (public benefit such as pest control, agriculture, or recreation); no single motive alone correctly captures the full explanation provided in the passage.