The image shows that the following matches have been made, indicated by the handwritten numbers next to the sentences:
Sentence C is matched with speaker 4.
Sentence D is matched with speaker 3.
Sentence E is matched with speaker 4.
Since the instructions state there is one extra sentence and speakers are numbered 1-4, and speaker 4 has two matches (C and E), there is likely an error in the provided markings or the original audio content is needed for a definitive answer. However, based on the markings:
This leaves sentences A and B as potentially the extra sentence, or there is a misattribution for speaker 4.