Sam runs a large chain of car repair shops. He pays his employees for 8 hours of work each day. The employees have to log the amount of time they spend working on each job, which results in a number of billable hours for each employee each day. Sam would like to estimate the mean number of billable hours for the large number of employees at the company. To do so, he selects a random sample of 10 employees and asks them how many billable hours they tend to have each day. From their responses, he constructs a 95% confidence interval for the true mean number of billable hours for all employees in the company. Which of the following may have an impact on the confidence interval, but is not accounted for by the margin of error? A) response bias
B) nonresponse bias
C) sampling variation
D) undercoverage bias