The scenario that is an example of a statistic is:
"Thirty students were randomly selected from Mrs. Calzada’s group of 158 students. They were asked how many hours they spend watching TV every day. The mean number of hours was 2."
This is because a statistic refers to a characteristic or measure obtained by using the data values from a sample (in this case, the 30 students), as opposed to a parameter, which would involve the entire population (like all 158 students).