I believe the answer is a
Answer:
invasive species are a problem both in anthropogenically altered and natural environments
Explanation:
An invasive species can be defined as a non-native species introduced into a new environment which then becomes abundant. Only in the US, it is believed that there are approximately 4,000 invasive species (some examples include the feral pigs, grey squirrels, European rabbits, etc.). In general, invasive species have a negative impact on the ecosystem, especially by displacing native species and thereby altering the trophic chain. In anthropogenically altered environments (anthromes), human beings are considered to be an invasive species.
In the human respiratory system, gas exchange occurs across the cells of the alveoli. Alveoli or an alveolus is the deepest part of the human respiratory system. This part of the respiratory system is a place where gas exchange between oxygen and carbon dioxide occurs from inhaled air to the blood cells<span>.</span>
The answer to the very question you are asking is "plants"
