The Following Information Was Obtained from Matched Samples Taken from Two

The following information was obtained from matched samples taken from two populations. The daily production rates for a sample of workers before and after a training program are shown below.Assume the population of differences is normally distributed. $\begin{array}{lll}\text { Worker } & \text { Before } & \text { After } \\1 & 20 & 22 \\2 & 25 & 23 \\3 & 27 & 27 \\4 & 23 & 20 \\5 & 22 & 25 \\6 & 20 & 19 \\7 & 17 & 18\end{array}$
Given that the null hypothesis to be tested is H₀: $\mu$ d = 0,

A) the null hypothesis should be rejected.
B) the null hypothesis should not be rejected.
C) the alternative hypothesis should be revised.
D) the null hypothesis should be revised.