Daily Bread (Daily) sells bakery products in PA. In doing so, Daily sales personnel solicit orders from customers, and the orders are sent to Daily headquarters outside PA for acceptance or rejection. Daily delivery personnel make deliveries in company-owned trucks. They also are authorized to accept returns of stale products, and, if needed, sell additional products to customers while at a customer location. Daily conducts no other activities in PA.

PA has assessed a net income tax against Daily based on its activities in the State. PA imposes a net income tax that is apportioned based on a taxpayer's sales apportionment factor (e.g. in-state sales as a percentage of total sales). The net income tax apportionment methodology applies equally to in-state and out-of-state businesses. However, there is a 50% tax credit granted for all corporations headquartered in PA during the tax year.

 

Under what prong of Complete Auto's 4-prong test would this tax regime be most susceptible to an argument that its imposition violates the this Clause?