The network is the set of devices, connections, protocols, and configurations that enable communication and data transfer between different systems and applications. The network can affect the performance of storage throughput by influencing factors such as bandwidth, latency, jitter, packet loss, and congestion. Poor network performance can result in low storage throughput in both IOPS and MBps, as it can limit the amount and speed of data that can be sent or received by the storage devices. Verifying the network should be the next step for troubleshooting the issue of slow storage throughput on a few VMs in a private IaaS cloud, as it can help identify and resolve any network-related problems that may be causing the issue. Reference: CompTIA Cloud+ Certification Exam Objectives, page 17, section 3.4

Regions are geographical locations or areas where cloud service providers have data centers or facilities that host their cloud resources or services. Regions can help reduce latency for all users when deploying a globally accessed application to the cloud, as they can enable faster and closer access to the cloud resources or services based on the user's physical location. Regions can also improve performance and availability, as they can provide redundancy and load balancing by distributing the workload across multiple locations. Reference: CompTIA Cloud+ Certification Exam Objectives, page 15, section 2.8

Detailed
C . Increasing storage IOPS: IOPS (Input/Output Operations Per Second) measures the speed at which storage can process data. Increased IOPS ensures the database handles higher transactional loads efficiently.
References:
CompTIA Cloud+ CV0-003 Study Guide Chapter 12: Storage in Cloud Environments.

Cloud bursting is a scalability model that allows a company to use a hybrid cloud environment to handle peak or unpredictable workloads. Cloud bursting involves using the private cloud to host the core or critical applications, and using the public cloud to provide additional or temporary resources when the demand exceeds the capacity of the private cloud .
Cloud bursting can help a company to:
Improve the availability and reliability of the applications by replicating them across multiple cloud platforms and locations .
Optimize the performance and efficiency of the applications by dynamically allocating and releasing resources based on the workload and traffic .
Reduce the cost and complexity of the IT infrastructure by leveraging the pay-as-you-go and on-demand models of the public cloud .