I already responded to these.How about the other two- the bottom composition affecting visibility more than current, and an OOA scenario where a diver is breathing off his buddies octo requiring an emergency ascent rather than a normal one.
- Bottom composition affects visibility because of the degree to which it reflects or absorbs light.
- We need the exact wording of the other one to judge, not just your vague description of it. I don't have a copy of the question with me now.