A small business currently has a server room with a large cooling system that is appropriate for its size. The location of the server room is the top level of a building.  The server room is filled with incandescent lighting that needs to continuously stay on for security purposes. Which of the following would be the MOST cost-effective way for the company to reduce the server rooms energy footprint？（）

• A、Replace all incandescent lighting with energy saving neon lighting.
• B、Set an auto-shutoff policy for all the lights in the room to reduce energy consumption after hours.
• C、Replace all incandescent lighting with energy saving fluorescent lighting.
• D、Consolidate server systems into a lower number of racks，centralizing airflow and cooling in the room.