Answer :
I would choose 'ambiguous' as the missing word if it is part of the distractors or a form of that word. By definition, ambiguous means - open to more than one interpretation, having a double meaning.
The correct answer is:
Ambiguous details are details that are open to interpretation.
The word "ambiguous" means open to more than one interpretation; not having one obvious meaning.
Since the details are not clear and explicit, the reader may interpret them in different ways.