Each scene is saved as: a. a unity project in the main file menu b. a prefab in the level editor c. an asset in the project view d. an object, in hierarchy view

A. a unity3d project in the main file menu.

Unity3d Scene is saved as a .unity file and it can be opned again as a project. The scene file contains all the references to assets , prefabs and other compenent and you can open the unity3d editor by opening this file. If you make any change in the unity3d editor you must have to save it in this file. In the latest version you can view the .unity3d file in the text editor.

i think its controle not shift

a local network will allow everyone in the office to share the printer.