Step 1: Understanding the Question:
The question asks for the reason behind the disciples' annoyance.
Step 2: Locating the Information in the Passage:
The passage connects the wife's action to the disciples' reaction.
It says, "She took a bucket of water and poured it on him... But his disciples were annoyed with the preceptress."
The word 'preceptress' refers to Socrates' wife. The annoyance immediately followed her action of pouring water on Socrates.
Step 3: Final Answer:
The disciples were annoyed because they perceived his wife's act of pouring water on Socrates as disrespectful towards their teacher, especially while he was in the middle of a discourse. They were angry on behalf of their master.