Online purchases have soared during the Chinese New Year holiday. It's the dead of winter in Shanghai. Delivery man Liu Jia and his colleagues start the day when most of people are still asleep. Working at a distribution point of a shopping website in Shanghai, they promise to deliver products within three hours of an order being placed. "I buy most of my grocery online, especially the heavy items. It's convenient and cheap compared to the supermarket in my neighborhood," Customer Chen Hong said. Orders such as these have increased for the New Year, forcing Liu Jia to work around the clock. "The orders are usually rice, laundry detergent , tissue paper and snacks, mostly food and articles for everyday use," Liu Jia said. According to an industry report, China's B2C (Business to Customer) online sales are growing at an annual rate of 25 percent. Competition between online giants like Taobao and Jingdong is now fiercer than ever. "The _ of online shopping is that customers can buy products easily. So the competition is about: firstly, the range of products; secondly, the depth under each category of products; third, the price and user experience," Pan Biao, vice president of YHD.  com, said. E-commerce is one of China's fastest growing sectors.  It's changed people's buying habits, and even their living habits. And it's had a huge impact on the retail industry. To make online shopping more convenient, major sites are investing heavily to build payment systems and logistics networks. On average, a retailer now can deliver goods to the majority of cities within 3 days, and to towns and more remote areas in the country within a week. "Competition will produce a number of good companies, making better products and services that customers need. In the field of E-commerce, we are leading the world in terms of products, services and industry development," Liu Yinbin, associate professor with Dept of Information Management, Shanghai University, said.  Experts also say customers are increasingly making their online purchases from mobile devices, opening up vast new opportunities and competition for retailers. Which of the following can be the best topic of the passage?
Customers like buying mobile devices. Online shopping increases rapidly for Chinese New Year. Most customers buy food and articles for everyday use. Taobao and Jingdong are competing fiercely.