Step 1: Concept
When converting from Active to Passive Voice in the Present Perfect tense ("has/have + V3"), the structure becomes "has/have + been + V3".
Step 2: Meaning
In Passive Voice, the object of the active sentence ("the details") becomes the subject.
Step 3: Analysis
The new subject "The details" is plural, so it requires the plural auxiliary verb "have" instead of "has".
Step 4: Conclusion
Therefore, the correct construction is "have been collected".
Final Answer: (C)