Based on the scenarios provided, the most likely outcome is:
The city of Paris will stop lighting the Eiffel Tower at night to save energy.
This option is plausible, especially in the context of ongoing discussions about energy conservation and sustainability initiatives in many cities around the world. The other options regarding the height of the Eiffel Tower or its lighting variations are less likely to be true. The Eiffel Tower's height does not change, and while lighting intensity might vary, it is less likely to be tied to specific months in such a manner.