The pattern of embryonic development in which only the cells lacking yolk subsequently undergo cleavage is called:

a and b

d is the answer

sorry if its wrong!

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.