Answer:
the example Is that if we see a plant it is made up of cells
Arwin in 1856 proved that all pigeon breeds do originate from the Rock Dove and through a process of regression you can recreate the Rock Dove, the ancestor of all pigeon breeds. Hopefully that helped
The nitrogenous bases placed in between the DNA double helix strands, like rungs on a ladder, are positioned there because of the hydrophobic effect and are stabilized by hydrogen bonding. The stability of DNA also relies on the interactions between the hydrogen bonds between bases, hydrogen bonds between bases and surrounding water, and base interaction between neighboring bases.
Hydrogen bonds are able to stabilize the DNA double helix by pairing up with their complementary base pairs (guanine with cytosine and adenine with thymine)
Hope this was able to help you! I went through my answer and bolded the more important parts, and parts more useful for answering the question.
I believe it is a. Birds typically migrate in the wintertime to escape harsher climates to places that have more food. Also, some birds migrate to certain places when they are about to start their nesting and breeding seasons.