The following information was obtained from matched samples taken from two populations. Assume the population of differences is normally distributed. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 The point estimate for the difference between the means of the two populations (Method 1 - Method 2) is:_______a. 0. b. 2. c. -2. d. -1