Which of the following describes a business-to-business (B2B) e-commerce transaction?

	1. An auto makers inventory management system automatically orders windshields from a glass supplier when stock gets low.
	2. A taxpayer submits an income tax return online.
	3. A companys payroll system automatically withholds payments for social benefits from an employees paycheque.
	4. A shopper buys a new computer from an online retailer.