Of the eight categories of protein, which is considered to be most important for the emergence of the earliest life forms ~3.5 billion years ago?

Enzymatic proteins bc they catalyze reactions and were important for evolution.

Explanation:

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.