Concept:A computer room requires a clean environment to protect hardware and reduce safety risks.
Explanation:Dust settles on internal components and blocks airflow, causing overheating or short circuits.
A dust-free room improves equipment reliability and reduces fire hazards.
Arranging chairs together or closing the door does not prevent dust or electrical danger.
Keeping liquids near computers creates a risk of spills and electric shock.
Thus, maintaining a dust-free environment is the correct safety measure.
Answer:D. maintaining a dust-free environment