Please help me out. u will get 18 points if u do and thank you so much if u help out:)

i think it would be A

hope that helped! :)

the real answer is b. scintillation counter

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.