The scaled factor has to be 2 because 4*2=8. You can check 2 is the correct answer by doing 8/2, which is 4. The scaled factor has to be proportional so if one side of ABC was 2 but the same side on ABC prime or A’B’C’ was 10 it would not be proportional, not a scaled factor. Because 2*10 is 5, not 8. But it does not give any other side lengths so it is 4.
