When you flex your muscles you are contracting them. When your muscle fibers gain tension through Actin and Myosin crossbridge cycling they may shorten due to the tension. This is called muscle contraction
Answer:
The answer would be A. Platelets
This is disconformity. There are different types or soil/dirt and disconformity is the line seen in the picture, its between 2nd and 3rd layer. <span />
All of the above assuming yo also have a good diet