The answer is Habitat. I'm 100% sure it is.
Answer:
B)Cyclins regulate the timing of cell cycle
Miller Urey experiment mimics the environment we had for earth billion of years ago. They put in inorganic molecules and came out with organic molecules. Other scientist thought that they messed up their experiment, but once other scientists recreated and tested. They saw that Miller and Urey were correct. And that helped them see that the origin of life can come from simple cells.
Circulatory system pumps blood from the heart to the lungs to get oxygen. The heart then sends oxygenated blood through arteries to the rest of the body. The veins carry oxygen-poor blood back to the heart to start the circulation process over. Your circulatory system is critical to healthy organs, muscles and tissues.
The answer to the question is A
