The e-mail usage for two different plants of a large company was compared at level of significance 0.05. A sample of 100 employees was selected at each plant. The mean number of e-mail messages sent per employee for one plant was 16 per week and the standard deviation was 4. For the other plant, the mean was 15 and the standard deviation was 3. For the test of equal population means versus unequal population means, the absolute value for the computed test statistic, the critical values, and the p-value respectively are:
a. 2, ± 1.96, 0.0455
b. 3, ± 2.33, 0.0027
c. 3, ± 1.96, 0.0455
d. 2, ± 1.65, 0.0455