The corticospinal tract, the corticobulbar tract, and the rubrospinal tract make up the of descending tracts from the primary motor cortex.

thinking it would be d not too sure but i think it's right

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.

because it travels in smaller waves then all other colors, causing it to be the most visible color