Astudent finds the slope of the line between (8, 17) and (1, 4). she writes 17-4/1-8 what mistake did she make?

a) she did not keep the order of the points the same in the numerator and the denominator.
b) she used y-values where she should have used x-values.
c) she mixed up the x- and y-values.
d) she should have added the values, not subtracted them.