The correct answer is B. The passage states a credible source, the General State Archives of Greece.
Step-by-step explanation:
The word "credibility" refers to a quality of sources especially documents whose information can be believed and trusted. In general terms, the elements that made a text or other source credible include a recent date as knowledge changes over time; an author that is expert on the topic and more importantly evidence such as statistics or reference to other reliable sources or authors that support the information included.
In the case of the passage presented, this passage explains the role of slaves and the conditions they lived in Greek society and for doing this, the author of the source refers to the "General State Archives of Greece" which is a compilation made by the government of Greece of documents related to the country and therefore a reliable and credible source. This means, the author of this passage supports the text by using another source and this makes this passage credible. Therefore, the feature that makes the passage seem credible is "The passage states a credible source, the General State Archives of Greece".