Which of the cloud cross-cutting aspects relates to the requirements placed on the cloud provider...

Whereas a contract spells out general terms and costs for services, the SLA is where the real meat of the business relationship and concrete requirements come into play. The SLA spells out in clear terms the minimum requirements for uptime, availability, processes, customer service and support, security controls and requirements, auditing and reporting, and potentially many other areas that define the business relationship and the success of it.