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

A small numerical value for the test statistic (in absolute terms), relative to the critical value would cast considerable doubt on the null hypothesis.

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

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.

Assume that we select independent samples from two normally distributed populations. If the sample means and standard deviations are known, then in order to test the difference between the population means we assume that the two population variances are equal.