The following information was obtained from matched samples.

Individual	Method 1	Method 2
1	8	7
2	4	7
3	4	6
4	6	5
5	3	5

The null hypothesis tested is H₀: _d = 0. The test statistic for the mean of the population of differences is _____.

a. -1.069

b. 0

c. 1.069

d. -1.195