I think there are a few things that you may be missing on the answers that everyone has provided to you. I hope this answer helps you.
There is a ton of potential answers to your question, we could talk about RAID levels, and how that is a DR solution for a bad disk. We could talk about hot sites, or cold sites. A DR solution has to be driven by the requirements that your customer has. You are going to have to sit down with them and help them answer the questions to make sure that it meets their requirements. Many clients are not going to understand some of the questions that you need to have answered. Things like acceptable data loss, acceptable recovery time, hot or cold site, or do you even need a DR Site.
I would recommend a multiple step approach, give them an example and ask them what they would like to have done, and what they must have done to not impact the revenue to their company. Base on the answers then you can begin with the next level of requirements gathering. Your messaged stated this was for an audit requirement. What is it?
If its for Audit Only and it has to be practiced every 6 months, then does a backup and restore of the databases meet the requirements? That is a very valid DR solution.