Which of the following would be the safest environmental condition for working on multiple systems at one time？（）

• A、A tiled room with anti-static mats and wrist straps.
• B、A clean， carpeted room with anti-static mats and wrist straps.
• C、A tiled room in a warehouse with outside ventilation.
• D、A clean， carpeted room with air purifiers and dehumidifiers.