Answer:
1. a. z test for means and t test for means.
2. C. HA : mu1 - mu2 > 0
Step-by-step explanation:
Hypothesis testing is used in a situation where there are more than 1 alternative available. The t test is conducted in the mean which determines the t value and then this value is compared with p value to identify the situation whether to accept or reject the null hypothesis. The alternative hypothesis in this situation is is represented by mu.