Buyline is an e-commerce web site. it has come up with a promotional offer where buyers get a 60 percent discount on refrigerators if a minimum of 100 buyers agree to buy the product within 24 hours of the offer being announced. in this case, it is evident that buyline is a _____.

a. group buying platform

b. peer-to-peer e-commerce platform

c. participatory e-commerce site

d. social networking sit