Why Are Police Interrogations Often Conducted in Small,bare,soundproof Rooms

Why are police interrogations often conducted in small,bare,soundproof rooms?

A) so that distractions will be minimized and the suspect will be better able to focus on the interrogation
B) so that suspects feel socially isolated and powerless
C) so that police operating costs will be kept to a minimum
D) so that other police officers will not become biased against particular suspects