Answer:
destruction of natural habitats
Explanation:
First let's define our main terms or each answer choice.
1)Decreased deforestation - Deforestation is the action of clearing mass amounts of trees for human use such as farms, buildings, houses etc. So this answer is basically saying that as the human population increased the amount of trees that get destroyed will decrease.
2)Destruction of natural habitats - Natural habitats is simply the natural home of animals. So this answer is saying as the human population increases the more number of animals natural homes will be destroyed
3)Unchanged climate - Climate is basically the long term weather of an area. So this answer choice is saying that as the human population increases the climate will remain unchanged.
4)Increased biodiversity - Biodiversity is the different kind of life on earth usually regarding a specific habitat or ecosystem. So this answer choice is essentially saying that as the human population increases the types of life on earth increases.
What comes with increased human population?
As the human population increases the need for food, houses, water, jobs etc increases as well. Keep that in mind while looking at the answer choices.
Determining the answer
Why the answer isn't A
Rereading 1) and then what comes with increased human population we can most definitely rule out A. As human population increases the need for houses and jobs increases. In order to have a good enough supply of wood and land for these houses and buildings for these jobs, deforestation must occur. So as human population increases deforestation would increase as well.
Why the answer is B.
Rereading 2) and then looking at what comes with increased human population we can maybe say that B is correct. Looking back at the previous section we've already identified that mass deforestation must occur to satisfy the needs for wood and land for houses and jobs for the increased population. As we know many animals probably live in these forests and inside of the trees so many of these animals homes would be destroyed resulting in the destruction of natural habitats ( animals homes )
Why the answer isn't C
After rereading section 3) and what comes with increased human population we can rule out C. If an increase in human population results in deforestation the amount of CO2 released into the air increases as well. If you didn't know trees absorb CO2 which is bad for the atmosphere. Once destroyed the trees release the CO2 that they have absorbed. CO2 and other green house gases create holes in our atmosphere leading to a change in climate as the suns radiation travels through these little holes. This results in a change in temperature, increased natural disasters and the melting of ice on the poles which also leads to increased temperatures. Deforestation isn't the only cause of this ( gasoline from cars, burning of fossil fuels , pesticides and many other human caused actions result in this ). These are all human caused things so if the human population increases the amount of green house gase emissions would likely increase as well meaning the climate would no remain unchanged.
Why the answer isn't D
After reading section 4) as well as the section titled "why the answer is B" we can rule out D. In order for an increase in biodiversity to occur, natural habitats must be preserved ( remain untouched ) if deforestation occurs then natural habitats will be destroyed and biodiversity will never increase as many animals may not be able to find another sustainable habitat. Not only that but the question asks about a negative affect and biodiversity is a good thing.