Answer: providing supporting evidence of a prince believed to be clever because he chose a good servant.
Step-by-step explanation:
You didn't give the passage or the options to the question. I got the options online and the correct answer has been chosen.
The text structure helped the author convey his central idea that a prince is judged by the quality of his servants by providing supporting evidence of a prince believed to be clever because he chose a good servant.
According to the author, the intelligence of a prince can be judged based on the kind of servants that the prince chooses.
In a situation whereby the prince choose a faithful servant, then it's believed that the prince posseses a high level of intelligence. An example was given about the prince of Siena who chose a faithful and hardworking servant and therefore was seen to be intelligent.