You are studying how tools have evolved through cultural evolution. you find several instances where groups with very different technologies meet and there is a transfer of technology from one group to the other. this is most similar to what process in biological

a) genetic drift
b) natural selection
c) mendelian inheritance
d) horizontal gene transfer

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.

the planets have a circular orbit around the sun.