Twenty different video games showing alcohol use were observed. The duration times of alcohol use ​(in seconds) were recorded.
1. When using this sample for a t-test of the claim that the population mean is greater than 89 ​sec, what does df​ denote?

A. The sample standard deviation
B. The number of degrees of freedom
C. The sample size
D. The test statistic
2. What is its​ value?