I believe it is gene sex chromosones...
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.
The answer would be:
C: all cells are similar in structure and function
<em>Even though this answer is correct in content, this was not mentioned in the main idea of cell theory.
</em>Hope this helps c:
