Joining an Information Sharing and Analysis Center (ISAC) is the best option because it provides a centralized resource dedicated to sharing and analyzing information about cyber threats, vulnerabilities, and incidents among its members. ISACs are sector-specific, which means the sharing is highly relevant to the organization's particular industry or sector. This specificity can lead to faster and more effective responses to threats. While the other options may also be helpful in certain contexts, they either lack the sector-specific focus or don't provide the same level of collaborative threat intelligence sharing.