问题如下：
Which of the following is the most accurate statements about hypothesis testing?
选项：
A. The calculated z-statistic for a test of a sample variance when the population variance isknown as: (σ2 is the variance).
B. If the computed z-statistic = -3 and the critical z-value = -2, the null hypothesis should be accepted.
C. Type I error equals the significance level.
解释：
C is correct.
The z-statistic is used for the test of a sample mean not variance .
If the computed z-statistic = -3 and the critical z-value = -2, the null hypothesis should be rejected.
选项C中的Type I error是指什么呢？