Answer:
DNA?
I'm guessing the boys who look the same are twins, since there's no photo of them..
Hope this helps
The answer is C.) Sac. More formally known as the amniotic sac. It's also sometimes called the bag of waters.
B. the addition of one phosphate group
Enzymes catalyze reactions by lowering the activation energy of the reaction. Enzymes are made of proteins, and therefore the answer here is B. Protein molecules.
