H.264 compression uses I-frames (intra-coded frames) as reference points, with P-frames (predictive frames) and B-frames (bi-directional frames) encoding only the changes from the previous frames. If a video contained no I-frames, there would be no reference frame for decoding, resulting in an inability to display any image.
This would theoretically result in a black image being visible during the whole video. Therefore, the correct answer is B. For more detailed information, refer to Axis Communications' technical notes on video compression.