The line of immune system was broken is the skin.
It may not look much but is an important part of the immune system.
D, all of the above. It depends on what kind of person you are, and the kinds of people you're friends with. Many people experience all of the above with their friends.
A newborn's skeleton is composed mostly of cartilage, which will ossify as the infant grows. It will be made if mire than 300 parts, many of which will combine into single bones.
