Question

Which of the following sentences should be added to the last paragraph to support the idea that today's human population levels are harming the Earth?

A.
If true, this would mean that the Earth's human population is going to keep increasing for hundreds of years to come.
B.
In other words, humans today have more access to air, food, and water than they did in the 1890s when the population was lower.
C.
Moreover, if fewer people lived on Earth, they would require less air, food, and water than people do today.
D.
For example, nearly 99% of North America's prairies have been cleared in order to grow enough food for the current population.
In the year 2011, Earth reached a huge milestone. The human population rose to 7 billion people. This growth seems incredible. The population was just 6 billion in 1999. This means the population increased by 1 billion people in only 12 years!
However thrilling this news may seem, it also has people worried. Many scientists doubt that the planet can support so many people. They think that Earth may be reaching its carrying capacity.
Carrying capacity is another way of saying maximum population. The idea was first introduced by Thomas Malthus in the 18th century. Carrying capacity has to do with balance. Just as a pond can only have so many fish, Earth can only have so many humans. The planet has a limited amount of air, food, and water. When these things are easy to get, the human population grows. When these things become scarce, or hard to find, Earth reaches its carrying capacity.
Sadly, there is proof that today's population levels are already harming the Earth. But it is important to remember that carrying capacity is not a fixed number. By taking better care of the planet, we might be able to support future population growth.

Answer 1

The most appropriate sentence to add to the last paragraph to support the idea that today's human population levels are harming the Earth is D. For example, nearly 99% of North America's prairies have been cleared in order to grow enough food for the current population.

Why is this correct?

Human activities, fueled by an expanding population, conspicuously damage the Earth's environment. The extensive clearing of natural habitats for agricultural purposes disrupts ecosystems, diminishes biodiversity, and significantly contributes to soil erosion and water pollution.

This vividly underscores the premise that the Earth's capacity to sustain life is under severe strain due to the burgeoning human population.