Which experiment most likely has greater reliability and why ?

Aprocedure done under controlled conditions to test a hypothesis is an inquiry.

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

Which line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise? 1.b,2.c,3.a,4.d