Answer: Grapevine
Explanation: Grapevine is an informal communication network in which the information does not flow in a prescribed and rule based structure. The information flows at every direction irrespective of the level of authority.
In the given case, Jeff initiates the information flow at lunch and not in an official meeting. Similarly Judy receives the information from the HR department employee although she do no work there.
Hence the information is flowing in every direction. Thus, the correct answer is grapevine.