What is Grapevine communication?

The correct option is Informal Communication.

Explanation:
Grapevine communication is a term used to describe the informal transmission of information, gossip, or rumors within an organization. Unlike formal communication channels, which follow official, pre-defined hierarchies and structures (such as memos, official emails, or reports), grapevine communication flows rapidly in all directions—upward, downward, and horizontally—without any set rules or channels.

It is called "grapevine" because the route of the information is distorted and looks like a tangled grape vine, making it difficult to trace the original source of the message. Since it relies on social relationships and casual interactions among employees, it is classified strictly as Informal Communication.