题目10单选题
The basic value proposition of community providers isA. they offer a fast, convenient one-stop site where users can focus on their most important concerns and interestsB. they offer consumers valuable, convenient, time-saving, and low-cost alternatives to traditional service providersC. they create a digital electronic environment for buyers and sellers to meet, agree on a price, and transactD. they increase customers' productivity by helping them get things done faster and more cheaply