The end of his round on Saturday was a -5, and the end of his round on Sunday was a 0.
It's D, because the mean doesn't matter as much if it's only taken in a small variability. The mean was selected from 25 random pages in the book, that is why it is right.
Y = -5x + 12 since the slope of that line is -5x and in order to pass through that point the y intercept must be 12