Citizen Kane is generally considered to be the first modern sound film because

A. it was the first film to make significant use of invisible sounds and dead tracks to strengthen the drama.
B. it offered an ironic voice-over narration instead of the traditional narration that had been used up to that point.
C. it conveyed a sense of three-dimensionality without the benefit of the multiple soundtracks and speakers required for true stereo.
D. it was the first film to use multi-track recording.

Answer: C