Quick Courier Services ("Quick") is a company with 25 employees located in the hypothetical state of Longville. Quick provides services to businesses that require documents or packages to be delivered on a same day basis. While most of these deliveries are made by car or van, Quick also employs several bicycle couriers to accommodate customers in large cities.

After a rash of bicycle courier accidents in several cities, Congress passed a federal statute that banned bicycle couriers. The statute is intended to protect the safety of the public at large. Congress justifies the statute on the basis that couriers are inherently involved in commercial activity. What enumerated power is Congress using as the basis of its authority to pass this statute? If Quick challenges the constitutionality of the statute, what would be their probable legal theory?