Online Law (Online) is a C Corporation and is subject to tax in Pennsylvania. Online provides remote litigation support services to law firms. Big Law Firm (Big) is a partnership headquartered in Pennsylvania where its procurement functions are also located. Big's accounting functions, including accounts payable processing, are located at its administrative service center in Florida.
 Big's procurement department ordered an Online subscription to allow Big's employees to access Online's services from locations around the country, but neither Big nor Online track where such access occurs.
 According to the Pennsylvania statute, what amount of Online's revenues from Big should be treated as being from Pennsylvania sources?

	a.	None because Big's billing address is in Florida.
	b.	4% because that is Pennsylvania's percentage of the national population.
	c.	100% because Big ordered the services through its procurement function in Pennsylvania.
	d.	The amount cannot be determined until Online's systems track physical access points.