Read the following passage and answer the question by choosing the correct options:
Since the last few decades, growth in human population has increased the rate of consumption of natural resources. It has accelerated the loss of species and habitation in different parts of the world. Tropical regions which occupy only about one-fourth of the total area of the world, contain about three-fourth of the world human population. Over-exploitation of resources and deforestation have become rampant to fulfil the needs of large population. As these tropical rain forests contain 50 per cent of the species on the earth, destruction of natural habitats have proved disastrous for the entire biosphere.
Natural calamities such as earthquakes, floods, volcanic eruptions, forest fires, droughts, etc. cause damage to the flora and fauna of the earth, bringing change to the biodiversity of respective affected regions. Pesticides and other pollutants such as hydrocarbons and toxic heavy metals destroy the weak and sensitive species. Species which are not the natural inhabitants of the local habitat but are introduced into the system, are called exotic species. There are many examples when a natural biotic community of the ecosystem suffered extensive damage because of the introduction of exotic species. During the last few decades, some animals like tigers, elephants, rhinoceros, crocodiles, minks and birds were hunted down mercilessly by poachers for their horn, tusks, hides, etc. It has resulted in the rendering of certain types of organisms as endangered category.
It can be inferred from the passage that:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Human beings are responsible for the change in biosphere.
The passage traces the damage to human activity: population growth has accelerated the loss of species, over-exploitation and deforestation are rampant, pollutants destroy sensitive species, exotic species are introduced into habitats, and poachers have pushed animals into the endangered category. Natural calamities play a part, but most of the causes named are human, so it follows that human beings are responsible for the change in the biosphere.
Why the Other Options are Incorrect?
Option 1: Tropical regions occupy only three-fourth of the area of the world. — Incorrect. Misread: tropical regions occupy about one-fourth of the world's area; three-fourth is their share of the world's population.
Option 2: Natural calamities do not change the biodiversity. — Incorrect. Contradicted: the passage says calamities such as earthquakes and floods damage plant and animal life, "bringing change to the biodiversity" of the affected regions.
Option 3: Exotic species are useful for the environment. — Incorrect. Contradicted: the passage gives the opposite view: natural communities have suffered extensive damage because of exotic species.