Answer:
2 and 100 million
Because of the difficulties with both defining and tallying the total numbers of different species in the world, it is estimated that there are anywhere between 2 and 100 million different species.
Answer:

Explanation:
An element only has <u>one</u> type of atom and cannot be broken down by chemical means.
Let's analyze the answer choices.
1. This has two types of atoms, so it cannot be an element. It has more than one type of atom.
2. This has two types of atoms that are bonded together. It cannot be an element because there is more than one type of atom and the bonds can be broken.
3. This has one type of atoms, so it is an element.
Therefore the best answer choice is 3.
Answer:
Intraspecific competition
Hope this helps!