A car dealer who sells only late-model luxury cars recently hired a new salesperson and believes that this salesperson is selling at lower markups. He knows that the long-run average markup in his lot is $5,920. He takes a random sample of 49 of the new salesperson's sales and finds an average markup of $5,320 and a standard deviation of $840. Assume the markups are normally distributed. What is the value of an appropriate test statistic for the car dealer to use to test his claim?

A. t₄₈ = -5.00

B. z = -5.00

C. z = -0.75

D. t₄₈ = -0.75