To maximize the probability of rejecting the null hypothesis, use:

a. high alphas, large samples, and one - tailed tests.

b. low alphas and two-tailed tests.

c. high alphas but low degrees of freedom.

d. low alphas and high Z scores.

a. high alphas, large samples, and one - tailed tests.

Step-by-step explanation:

In a hypothesis testing, we find out test statistic and also p value.

The p value if less than alpha, we reject null hypothesis.

p value for one tailed would be half of p value for two tailed. So p being less than alpha is more in one tailed test.

Therefore, to reject the null hypothesis we must have p value less than our alpha.

If alpha is fixed high, the chances of rejecting the null hypothesis.

Similarly if one tailed is having p value less than two tailed, then chances of rejecting H0 are more. If sample size is small, margin of error would be more thus rejection for null hypothesis becomes lower.

Hence correct answer is

a. high alphas, large samples, and one - tailed tests.