What could limit the cloud service availability for multiple virtual machines under high loads?

Memory overcommitment can significantly limit the availability of cloud services for multiple virtual machines under high loads. When memory overcommitment occurs, more virtual memory is allocated to virtual machines than is physically available on the host system. This can lead to a situation where active virtual machines don't have enough physical memory to operate efficiently.

As the demand for memory resources increases during high loads, the hypervisor may need to swap memory pages to disk or resort to memory ballooning, both of which can result in increased latency or even service interruptions. Consequently, this can cause a degradation in performance and potentially lead to application failures or crashes, negatively impacting service availability.

While the other choices also represent factors that can influence performance, memory overcommitment stands out in its direct effect on the ability of multiple virtual machines to maintain performance under high workloads, as it deals specifically with the allocation of critical resources that support the operation of those VMs.