Answer:
According to the “hygiene hypothesis,” the problem with extremely clean environments is that they fail to provide the necessary exposure to germs required to “educate” the immune system so it can learn to launch its defense responses to infectious organisms. Instead, its defense responses end up being so inadequate that they actually contribute to the development of asthma.
Explanation:
I think that it is the bone system please tell me if right
Answer:
As competition increases and resources become increasingly scarce, populations reach the carrying capacity (K) of their environment, causing their growth rate to slow nearly to zero. This produces an S-shaped curve of population growth known as the logistic curve (right).
Explanation:
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C is the proper answer. They have been reduced by using unleaded gasoline because lead can harm the air and water we breathe, so using less of it will help reduce the pollution being caused by it.