Helicase "unzips" the two strands of DNA. During DNA replication.
So they respond by releasing hormones that stimulate the body to retain sodium and water. Blood vessels fill with additional fluid, and blood pressure goes up. The narrowing in one or both renal arteries is most often caused by atherosclerosis, or hardening of the arteries.
The lack of iron makes them crave ice.
What is A B C and D? You have to tell us what the options are so we can answer.