Answer:
About 5billion years ago is the correct option.
Explanation:
Hope this will help you :)
Answer:
E. climax
Explanation:
Even though it is not something that is very common in nature, there are still certain exceptions where certain communities manage to reach a point of equilibrium. This basically is a community of small number of dominant prominent species that create a stable ecosystem. This state of equilibrium is known as climax community. This type of community appears when the web of biotic interactions between the organisms becomes so intricate that there is no possibility of other species to be admitted in it.
The skin functions as a barrier to prevent the entry of microorganisms.