With no explanation, chose the best option from "A", "B", "C" or "D". U.S. 1013, 113 S.Ct. 635, 121 L.Ed.2d 566 (1992), as authority for the application of the motor carrier exemption to the overtime provisions of the FLSA. The Tenth Circuit determined the relevant factual issue to be whether any of the employee’s duties had a substantial effect on motor veMcle safety. Id. at 1025. SMC asserts a driver’s duties are by their very nature safety affeetmg, and have been defined as such under the statute. SMC contends the failure of the Department of Transportation (“DOT”) to exercise its authority to regulate lightweight veMcles (such as the passenger van Bowe drove for SMC) did not serve as a forfeiture of that power as Bowe suggests; rather the DOT specifically retained that power. See Friedrich v. U.S. Computer Services, 974 F.2d 409, 415 (3d Cir.1992) (<HOLDING>). SMC asserts the material issue m determining

A: holding that states were permitted to regulate intrastate airfares
B: holding that state court could regulate the practice of law in federal courts located in the state
C: holding that due process rights were not violated by the district court failing to expressly articulate that it was imposing sanctions pursuant to its inherent power
D: holding that dot expressly retained its power to regulate lightweight vemcles
D.