Explanation
Service level agreements (SLA) will be most effective in ensuring that Internet service providers (ISPs) comply with expectations for service availability. Intrusion detection system (IDS) and spam filtering services would not mitigate (as directly) the potential for service interruptions. A right-to-audit clause would not be effective in mitigating the likelihood of a service interruption.

Explanation
Two-factor authentication through the use of strong passwords combined with security tokens provides the highest level of security. Data encryption, digital signatures and strong passwords do not provide the same level of protection.

Explanation/Reference:
Explanation:
Listing all possible scenarios that could occur, along with threats and impacts, will better frame the range of risks and facilitate a more informed discussion and decision. Estimated productivity losses, value of information assets and vulnerability assessments would not be sufficient on their own.