There seems to be a typo. The answer should be (x,y) --> (x-8,y+1) This matches closely with choice D but it's not a perfect match.
If we plug x = 4 into the expression x-8, we get x-8=4-8 = -4, which is the x coordinate of D'
Do the same for y = 1 and we get y+1 = 1+1 = 2, the y coordinate of D'
You'll have to talk to your teacher about the typo. It's likely your teacher meant to write y+1 and the intended answer is choice D. Though I'm not 100% sure as the typo might point the answer somewhere else.
