it needs to happen because the old cells need to make new cells, so the cell copys its DNA and splits, then making 2 cells, and then that cell splits, making 3 new cells with the same DNA, and the chain keeps on going.
When cells asexually reproduce they split off from itself, and they have to replicate their DNA so both cells will have it because DNA is what tells the cell what to do, and how to work. The DNA will tell the cell parts all how to do their jobs, and will let the cell know when it should split off from itself. The DNA controls everything in the cell so without it the cell wouldn't know what to do.
The answer is A because there are many different types of finches. There are many different types of finches because they all have a different habit which encouraged them to adapt just to survive.