Explain how you found the answer (:

Look at point E which is located at (8,2). Then look at point E' which corresponds to point E. The point E' is located at (-2,0).

To move from E to E' we do the following: 
a) Shift 10 units to the left
b) Shift 2 units down
The "10 units to the left" move has 'x' turn into 'x-10'. Similarly, the "shift 2 units down" means we have 'y' turn into 'y-2'

So overall, the rule used is the rule shown in choice B. Which is why choice B is the answer. 

45 this is because of the agarose