Most of the competition that occurs in our ecosystem is basically just for survival. Breaking down into food supply, shelter, mate, etc. For frogs and birds, the thing that they are competing is the food supply. Given that they could live very near to each other, they will be competing for insects or other smaller animals.
Hyphens are used to link words that function as a single adjective before a noun. They are used with compound numbers, and to avoid confusion or awkward letter combinations. Hyphens are also used with certain prefixes and suffixes and/or in specific circumstances.
The correct answer is B.
Answer B describes a life outside of mankind, a life of independence. Answer B describes the life of someone who does not rely on anyone else.
