The correct answer is: D. Videoconferencing
Videoconferencing is a telecommunication technology that allows two or more people to communicate with each other via two-way video and audio, typically over the Internet. It can be used for a variety of purposes, such as business meetings, education, and healthcare.
Payment gateway is a system that authorizes payments for e-commerce transactions. It is a secure online payment processing system that authorizes credit and debit card transactions.
Blog is a website that contains articles, typically written in chronological order, often displayed in reverse chronological order.
Email is a method of exchanging digital messages, typically consisting of text and images, between two or more users.