Final answer:
If an Azure customer's service falls below the SLA's guaranteed uptime, they are entitled to receive a credit for the downtime, according to the terms outlined in the SLA.
Step-by-step explanation:
If a paying Azure customer experiences a monthly uptime percentage that falls below the guaranteed level as outlined in their Service Level Agreement (SLA), the customer is generally entitled to a compensation. The correct answer to this question is b) They are entitled to a credit for the downtime. This means that in the event of a service disruption that breaches the promised uptime percentage, the customer can request service credits that apply to future billing cycles. It's important to note that the specific terms, including how to claim these credits and any limitations or exclusions, should be carefully reviewed in the SLA provided by Microsoft Azure.