The standard term used to describe online communication and marketing tools is platform.
A platform is a software environment that provides the foundation for the development and delivery of applications and services. It is a set of tools and services that support the creation, distribution, and consumption of digital content. Platforms can be used for a variety of purposes, including communication, marketing, collaboration, and entertainment.
The other options are not as comprehensive or specific. User-generated content is content that is created by users of a platform, such as social media posts or blog comments. Network refers to the interconnected systems that make up the internet. Social media is a type of online platform that allows users to connect and interact with each other.