What must be true for natural selection to happen?

Which sequence correctly shows the path of carbon dioxide during repiration?

Draw the farm's ppf for corn and beef. draw a point that shows an inefficient combination of corn and beef. label ita. draw a point that shows an unattainable combination of corn and beef. label itb. draw a point that shows an efficient combination of corn and beef. label itc.

Ascientist wanted to formulate a pill to attack a specific type of bacteria that infects the throat. which biological component would be best to use as a model for the pill's function? bacteriocytes phagocytes complement antibodies