White blood cells are an important component of our immune system. One thing they do is consume and destroy bacteria by extending their plasma membrane around the bacterium and bringing it inside the cell in a vesicle. By what process do they engulf the bacterium?

Phagocytosis

Explanation:

During the process of phagocytosis, certain white blood cells called phagocytes (macrophage, neutrophil), extends their plasma membrane and draw in bacterium or other invaders into its own vacuole, digesting and destroying them.

Thereafter, the waste products containing weakened toxins are expelled from the cell through the cell membrane.

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.

i think the answer is a.keratin is the pigment responsible for skin color.