A company is interested in knowing the effects of a computer-training program. The company randomly selected 25 employees and measured their computer skills before and after the training program. To test the hypothesis, H₀: µ₁ = µ₂, the test statistic is a:
A) z-statistic.
B) t-statistic with 49 degrees of freedom.
C) t-statistic with 23 degrees of freedom.
D) chi-square statistic with 23 degrees of freedom.