I would say the answer is 4
The word alone can be read several ways this is suggested by "To me alone..." she is stating that only in her opinion it is a time or pause. Hope this helps!
Answer:
confidentiality: This mean a private stuff or a private document
Expert witnessing: This means a professional seeing something directly
Engineers' approach to risk: This means an Engineer going to a dangerous place
Participle, correctly punctuated.
