Which of the following best represents e-commerce?

E-commerce encompasses the buying and selling of goods and services over the internet. This involves various transactional activities, including online shopping, electronic payments, and the transfer of data for those transactions. The focus is specifically on commercial transactions conducted online, which is precisely captured in the option discussing buying and selling on the web.

This definition highlights the nature of e-commerce as it involves not just browsing or interacting but actively engaging in transactions that result in the exchange of products or services for payment. Other options, while they may involve technology and online platforms, do not specifically focus on the commercial aspect that defines e-commerce. Online gaming, social media interactions, and sending instant messages are primarily entertainment or communication activities rather than transactions that facilitate commerce.