When making an inference about two population means based on two samples, which of the following is not true?

Group of answer choices

If both sample sizes are greater than 30, the population variances are assumed to be known and a two sample Z test can be performed.

If one or both of the sample sizes are less than 30, a two sample t test should be performed.

To determine if it is plausible that the population variances from which two samples are take are equal, the F test for variances can be performed

None of the other responses. (All statements are true.)