Answer: The likelihood of rejecting the null hypothesis when it is true decreases.

## Explanation When the level of significance (α) is decreased: - **Type I Error (α)**: This is the probability of rejecting the null hypothesis when it is actually true. Decreasing α directly reduces the probability of making a Type I error. - **Type II Error (β)**: This is the probability of failing to reject the null hypothesis when it is actually false. Decreasing α typically increases β (the probability of Type II error), because the test becomes more conservative and less likely to reject the null hypothesis. - **Power of the test (1-β)**: This decreases when α decreases, making the test less powerful at detecting false null hypotheses. **Analysis of options:** - **A**: Correct - Decreasing α reduces the likelihood of rejecting a true null hypothesis (Type I error) - **B**: Incorrect - The likelihood of Type I error decreases, not increases - **C**: Incorrect - The null hypothesis is rejected less frequently, not more frequently - **D**: Incorrect - The likelihood of Type II error typically increases, not decreases Therefore, option A is the correct answer.

Author: LeetQuiz Editorial Team