Answer:
The Food-chain.
Explanation:
For example, animals at the top of the food-chain, in their ecosystem, balance the population. The organisms at the bottom are the producers. Herbivores usually eat the producers which are multiple types of plants. Omnivores and herbivores are prey for the carnivores, but they are also predators to the herbivores. That's all I could really think of... :)
I managed to find your options somewhere on the Internet: ebooks, hard cover books, mass market books, and paperback books.
I believe the most expensive form of books among these options are hard cover books. First of all, they take longer periods of time to be made; secondly, they need firmer materials because their first page is not easily bent as that in mass market books (which is just a smaller and cheaper version of paperbacks) or ebooks, which are electronic, so it doesn't take a lot of money to make them.
An metaphor is saying something is something that it isn't really. e.g. it was the cloud to my day. so the answer is c. s nature is not a delicious treat. hope this helped and I apologise if this is incorrect!
On email because you can send someone something on your computer in less then 3 seconds and also our society is always anxious about receiving a email or notification so email is better
