The correct answer is: A. AWS
AWS, or Amazon Web Services, is a cloud computing platform that provides infrastructure and services to businesses and individuals. It is not an online chat software.
Internet Relay Chat (IRC) is a text-based chat system that allows users to communicate with each other in real time. It is one of the oldest and most popular online chat software.
Google Talk is a discontinued instant messaging service developed by Google. It was originally a part of Google+, but was later spun off into its own service. Google Talk allowed users to send text messages, photos, and videos to each other.
Slack is a cloud-based messaging platform that allows users to communicate with each other through text, voice, and video. It is popular among businesses and teams for its ability to keep track of conversations and share files.