The scientific law?
a) is sometimes true in some places.
b) is sometimes true in all places.
c) is always true in some places.
d) is always true in all places.

i dont know this but ask your teacher for !

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.