Answer 1, authority 100%
HANDLE is a handle, i.e. a number that can be used to identify the resource. Using descriptors, you can refer to windows, kernel objects, graphic objects, etc.
Answer 2, authority 31%
You are not working directly with the device context. By itself, the context of the device is a “black box” that it has inside, we do not know. The device context has a handle (identifier), which, for example, are returned by the CreateDC and GetDC functions and which can be passed to other WinAPI functions.
Answer 3, authority 12%
Any context can be designated by a handle, but not every handle refers to a device context.