Which of the following are true when testing the difference between two means?

a. If the p-value is close to zero, then it is considered likely that the two population means are equal.

b. The fundamental nature of both the hypothesis testing and estimation is altered when we are dealing with the difference between two variables rather than one variable.

c. A large numerical value for the calculated test statistic relative to the critical value (in absolute terms) would result in a decision to reject the alternate hypothesis.

d. Because the variances in the populations are assumed equal, the sample variances may be pooled.