According to Media Richness Theory, richness is based on:

The correct choice aligns with the principles of Media Richness Theory, which posits that the effectiveness of communication mediums depends significantly on their ability to convey nuanced information and facilitate immediate feedback. Richness is determined by factors such as the number of feedback channels available, the personalization of the messages, the capacity for message variety, and the degree to which the communication medium can handle asynchronous interaction.

Feedback channels are vital because they allow participants to respond to messages in real-time, enabling clarification, discussion, and adjustment of misunderstandings. This enhances the overall communication effectiveness, making the medium richer when it offers several pathways for interaction and response. In contrast, mediums with fewer feedback opportunities tend to be considered less rich and therefore less effective in conveying complex messages or facilitating deeper discussions.

The other aspects mentioned in the other choices—like message complexity, language simplicity, or frequency of communication—do not directly contribute to the understanding of richness in the context established by Media Richness Theory. While they are elements that can influence communication, they do not encapsulate the integral concept of richness as defined by the responsiveness and feedback mechanisms provided by various media.