How Did Orson Welles Create More Immersive Sets in Citizen

How did Orson Welles create more immersive sets in Citizen Kane (1941) to lend their settings a more expansive spatial quality?

A) He shot the interiors in black and white.
B) He built only the minimum parts of the rooms needed to accommodate the story action.
C) He built a complete set of four walls for shots captured from high angles.
D) He used actual locations that he had reconstructed on a soundstage.
E) He used a Steadicam to provide moving, close-to-the-floor point-of-view shots.