Yes, it is possible that the DNS update may take only a few minutes to propagate, but it can also take up to 48 hours or more in some cases. However, if we consider the specific scenario described in the question, where the retail website is the only source of revenue for the organization, it is likely that they have already implemented a robust DNS infrastructure with fast propagation times and low TTL values.
In this case, updating the Border Gateway Protocol (BGP) autonomous system number (ASN) would likely take the most time, as it requires coordination with ISPs and can take several hours to propagate throughout the Internet. Therefore, the correct answer would be C - Update the Border Gateway Protocol (BGP) autonomous system number.